Abstract: BaNi2As2\, grown through a self flux method\, was studi
ed using transport along with nuetron and x-ray scattering methods. These e
xperiments revealed a complex interplay between Superconductivity and newly
discovered charge density wave phases when doped with Co (on the Ni site)
and Sr (on the Ba site). The phase diagrams from both substitution families
show a superconducting enhancement with an \;accompanying charge densi
ty wave suppression with increased doping. The lack of any known magnetic s
tructures in these compounds makes them ideal candidates for studying the c
ompetition between charge order and superconductivity. \;
=========================================
==============
Speaker: \; Neves\, Paul (Butch)
Title: \;Investigating Magnetic Skyrmions in (Cu1-XZnX)2<
span>OSeO3
Abstract: \;
\;In certain magnetically ordered materials\, an applied
magnetic field can give rise to topologically protected spin textures known
as magnetic skyrmions. These substances could potentially find future appl
ications in high density data storage\, and offer interesting insights into
the exchange interactions within magnetic materials. \;Cu2OSeO3 \;has recently received significant \;attention as the on
ly known insulating skyrmion material\, offering interesting insights into
the magnetic exchange interactions within magnetic materials. Magnetization
studies have suggested that Zn substitutions on the Cu site can split the
skyrmion phase into two separate temperature/field regions. However\, the s
kyrmion phase splitting in (Cu1-XZnX
)2OSeO3 \;has not been directly confirmed with structural measuremen
ts\, and the mechanism for this split is unclear. In this talk\, I discuss
our work to synthesize and characterize (Cu0.9Zn<
/span>0.1)2OSeO3<
/span>\, results from our magnetization and small angle neutron scatt
ering (SANS) measurements\, and their ramifications.==
====================================================
LAST-MODIFIED:20190109T201341Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150309T160000
DTEND;TZID=America/New_York:20150309T175000
DTSTAMP:20260416T023943Z
UID:gr7ovnvmgo3so00u0full3btg8@google.com
RECURRENCE-ID;TZID=America/New_York:20150309T160000
CREATED:20150127T161958Z
DESCRIPTION:Speaker: Holly Tinky (Appelbaum)\nTitle: Challenging the spi
n accumulation interpretation of local '3T' measurements\nAbstract: The re
cent observation of magnetoresistance in local ``three-terminal" (3T) measu
rements on ferromagnet/ insulator/ semiconductor junctions have spawned man
y claims of direct bulk spin injection or ``accumulation". We present a sel
f-consistent model to rigorously calculate expected voltage changes due to
electrochemical potential splitting from spin accumulation driven by pure e
lastic tunnel injection in such junctions\, and find that the experimentall
y observed magnetoresistance vastly exceeds theoretical predictions in all
doping\, temperature\, and bias voltage regimes. Our own experimental measu
rements using inelastic electron tunneling spectroscopy reveal that extrins
ic impurities and defects within the junctions are responsible for the obse
rved magnetoresistance signals\, which cannot possibly be attributed to spi
n dephasing of polarized bulk electrons from elastic injection as claimed b
y proponents of the method.\n\nSpeaker: Yaniv Rosen (Osborn)\nTitle: L
aser made from a superconducting lumped-element resonator and random defect
s\nAbstract: Two-level systems (TLSs) in dielectrics are a major source o
f energy loss for superconducting qubits and resonators at millikelvin temp
eratures. Using tunable bias-bridge resonator circuits\, we can sweep the e
nergy of the TLS ensemble with a dc electric field\, while simultaneously a
pplying an ac microwave field. We show that when applying a dc electric fie
ld sweep\, the TLS - microwave field system undergoes an inversion process.
The experiment is further extended to include multiple microwave frequenci
es where we explore the transfer of photons from one frequency to another u
sing a stimulated process between the TLS and the microwave field. This exp
eriment shows that the background of disordered TLS\, usually thought of as
deleterious\, may create potentially useful phenomena.\n\n
LAST-MODIFIED:20150504T213425Z
LOCATION:Toll 1201
SEQUENCE:3
STATUS:CONFIRMED
SUMMARY:PHYS 838C - CNAM Seminar Series
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151109T160000
DTEND;TZID=America/New_York:20151109T175000
DTSTAMP:20260416T023943Z
UID:lbg0jjlt95qgb660qgasop9f1k@google.com
RECURRENCE-ID;TZID=America/New_York:20151109T160000
CREATED:20150827T172216Z
LAST-MODIFIED:20240912T112346Z
LOCATION:1201 Physics
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C: Shangjie Yu and Renxiong Wang
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20151019T200000Z
DTEND:20151019T215000Z
DTSTAMP:20260416T023943Z
UID:7cs0qodu7st1cfgmslmkm9m26g@google.com
CREATED:20151013T162047Z
DESCRIPTION:SPEAKER: Halyna Hodovanets\n\nTITLE: Anisotropic transport and
magnetic properties of CeAuBi2 single crystal\n\nABSTRACT: \nIn this talk\
, I will present detailed temperature- and field- dependent data obtained f
rom magnetization\, resistivity and heat capacity measurement performed on
single crystals of CeAuBi2. The compound orders antiferromagnetically at ∼
13 K and shows large magnetic anisotropy at low temperature with an easy ax
is being along the c-direction. The field dependent magnetization data at l
ow temperatures reveal the existence of a spin-flop transition for H||c (Hc
∼ 75 kOe and T = 1.8 K). The zero-field resistivity and heat capacity dat
a show features characteristic of a Ce-based intermetallic with crystal ele
ctric field splitting and possible correlated\, Kondo lattice effects. The
constructed T-H phase diagram\, for the magnetic field applied along the ea
sy\, [001]\, direction shows that the magnetic field required to suppress T
_N below 0.5 K is ~ 75 kOe. The possibility of realization of the field-tun
ed quantum critical point (QCP) in CeAuBi2 will be discussed.\n------------
---------------------------------------------------------------\n\nSPEAKER:
Hyunsoo Kim\n\nTITLE: Superconducting states in non-centrosymmetric half
-Heusler YPtBi\n\nABSTRACT: Noncentrosymmetric half-Heusler RPtBi (R = rare
earth) compounds have been attracting much attention after theoretical pre
diction of a strong band inversion which makes these compounds a topologica
l insulator or semimetal. Recently\, superconductivity was discovered in Lu
PtBi and YPtBi with anomalous superconducting properties which may be relat
ed to its topological nature. However\, the superconductivity in these comp
ounds is poorly understood to date. Here I present experimental results of
angle dependent magnetoresistance and temperature variation of London penet
ration depth in YPtBi. The angular dependence of quantum oscillation freque
ncies in magnetoresistance show angle dependent beating of two spin-split F
ermi surfaces likely due to the strong antisymmetric spin-orbit coupling. T
emperature variation of London penetration depth is consistent with existen
ce of line nodes in the superconducting energy gap. Based on these experime
ntal observations\, I will discuss possible superconducting gap symmetries
in YPtB
LAST-MODIFIED:20151013T162104Z
LOCATION:1201 John S Toll Physics Bldg.
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C: Halyna Hodovanets and Hyunsoo Kim
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20200914T200000Z
DTEND:20200914T213000Z
DTSTAMP:20260416T023943Z
UID:1ea9jv759tq49c03q453jjri64@google.com
CREATED:20200908T175732Z
DESCRIPTION:Speaker: Dr. Johnpierre Pagli
one
Dr. Paglione will be giving an overview of the PHYS 838C Sem
inar. \;
Zoom Link&n
bsp\; \;&\; Meeting Info
Meeting ID: 911 9803 7643
\;
Password:558484 \; \;
LAST-MODIFIED:20201014T144328Z
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS 838C Seminar: Johnpierre Paglione\, UMD
TRANSP:TRANSPARENT
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150323T160000
DTEND;TZID=America/New_York:20150323T175000
DTSTAMP:20260416T023943Z
UID:gr7ovnvmgo3so00u0full3btg8@google.com
RECURRENCE-ID;TZID=America/New_York:20150323T160000
CREATED:20150127T161958Z
DESCRIPTION:Speaker: Yi Wang (Takeuchi)\nTitle:\nAbstract:\n\nSpeaker: Tr
istin Metz (Paglione)\nTitle:\nAbstract:\n
LAST-MODIFIED:20150504T213425Z
LOCATION:Toll 1201
SEQUENCE:3
STATUS:CONFIRMED
SUMMARY:PHYS 838C - CNAM Seminar Series
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20231016T200000Z
DTEND:20231016T210000Z
DTSTAMP:20260416T023943Z
UID:1c25bef64flh47c70ksvvnrfv5@google.com
CREATED:20230821T193036Z
DESCRIPTION:Title: Investigating the surface magnetotransport propert
ies of a single crystal topological kondo insulator candidate
Abstract: Over the last few decades\, extensive study of over a dozen f-e
lectron based Topological Kondo Insulator (TKI) candidates\, such as SmB6 a
nd Ce3Bi4Pt3\, have led to a deep understanding of the role localized f-ele
ctrons play in the formation of a robust bulk correlated energy gap along w
ith topologically protected surface conduction states in these materials. R
ecently\, however\, the observation of surface states and Kondo-like behavi
or in some d-electron materials is beginning to motivate further research t
o expand the understanding of TKIs into a new class of potential TKIs which
include FeSi and FeSb2. Using the inverted resistance method of separating
bulk and surface contributions to electronic transport\, our recent result
s have unambiguously demonstrated direct evidence of metallic surface condu
ction in FeSb2 at low temperatures\, revealing 2D metallic behavior on the
surface of an extraordinarily robust insulating bulk single crystal. We ha
ve expanded this effort to probe the magnetic field dependence and symmetry
of the surface conduction states in FeSb2 while investigating the contribu
tions to the transport behavior from intrinsic crystalline anisotropy as we
ll as extrinsic surface and bulk defects.
Advisor: Paglione
Location: Toll Physics Room # 1201
Time: 4pm -5:00pm
LAST-MODIFIED:20231004T064448Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Jarryd Horn
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200427T160000
DTEND;TZID=America/New_York:20200427T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20200427T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker: \;Yun Suk Eo
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C: No Class
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240318T160000
DTEND;TZID=America/New_York:20240318T170000
DTSTAMP:20260416T023943Z
UID:0a2690n68q78l6vnuatbc29u6s@google.com
RECURRENCE-ID;TZID=America/New_York:20240318T160000
CREATED:20240123T155408Z
LAST-MODIFIED:20240123T155510Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Spring Break
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190325T160000
DTEND;TZID=America/New_York:20190325T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20190325T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker 1: Jingnan Cai\nAdvisor: S. Anlage\nTitle: Design of RF
SQUID and Quantum Transmission Line Metamaterial\nAbstract: \nSQUID lattic
e serves as a strong candidate for metamaterial in radio frequency range\,
due to their subwavelength dimensions\, low dissipations\, large nonlineari
ties\, and high tunability. Inspired by the experimental observations of th
e multistability in RF SQUID metamaterial\, recent numerical works predict
the existence of chimera states in these structures under external driving
field. New generation of RF SQUID metamaterial with the theoretically propo
sed parameters as well as strong and positive coupling was designed. Despit
e the apparent complexity of their collective behaviors\, the theory behind
these RF SQUID meta-atoms\, the RCSJ model\, is surprisingly simple. On th
e other hand\, of more interest to the fundamental physics research is thei
r quantum analogue: qubits. By embedding these meta-atoms in a transmission
line\, the quantum transmission line (QTL) metamaterial provides a unique
opportunity to investigate emergent quantum phenomena\, due to the strong q
ubit-photon coupling as well as the quantum mechanical nature of such inter
action. Here we report the first step towards the realization of QTL metama
terial: the design of a single flux qubit in a coplanar waveguide.\n\n\nSpe
aker 2: Lance Boyer\nAdvisor: V. Yakovenko\nTitle: A Probe of Time-Reversal
Symmetry Breaking in Superconductors using a Corbino Disk Geometry\nAbstra
ct:\nSuperconductors that break time-reversal symmetry (such as Sr2RuO4\, U
Pt3\, URu2Si2\, PrOs4Sb12\, and Bi/Ni bilayers) are expected to exhibit a s
pontaneous Hall effect without an applied external magnetic field. However\
, the effect cannot be measured using the conventional Hall bar geometry be
cause of shunting by supercurrent. Instead\, we propose a Corbino disk geom
etry\, where a superconducting annulus is threaded by a solenoid carrying a
low-frequency ac current. The oscillating magnetic flux in the solenoid in
duces a circular electric field inside the superconductor\, which\, in turn
\, induces oscillating radial current due to the Hall effect. We investigat
e whether the induced radial charge oscillations can be detected using a co
axial waveguide.
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170213T160000
DTEND;TZID=America/New_York:20170213T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170213T160000
CREATED:20170131T205940Z
DESCRIPTION:Speaker: Joshua Higgins\nAdvisor: R. Greene\n\nSpeaker: Trist
in Metz\nAdvisor: J. Paglioine
LAST-MODIFIED:20170201T225609Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220214T160000
DTEND;TZID=America/New_York:20220214T173000
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs_R20220207T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20220214T160000
CREATED:20220121T185706Z
DESCRIPTION:Title: \;Nematicity and Strain Tec
hniques
Abstract: \; \;"Electr
onic nematicity is a relatively new topic of research and is often very rel
evant to strongly correlated electron systems. Studies show there is intere
sting interplay between nematicity and other phases\, like superconductivit
y\, charge and spin density waves. Even without nematic order arising in a
system\, nematic fluctuations can have strong effects on material propertie
s. I will give a brief introduction to electronic nematicity and follow up
by discussing some commonly used strain techniques."
<
br>
In-Person Location: Toll Physics Room # 1201
Time: 4pm -5:30pm
Zoom LInk:
\;https://umd.zoom.us/j/97
265681008
LAST-MODIFIED:20220209T170054Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Danila Sokratov
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170220T160000
DTEND;TZID=America/New_York:20170220T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170220T160000
CREATED:20170131T205940Z
DESCRIPTION:SPEAKER: Luke Robertson\nAdvisor: B. Kane\n\nTITLE: Quantum po
int contacts for electrons on H-Si(111) surfaces using a Ga focused-ion bea
m for direct-write implant lithography\n\nABSTRACT: Quantum point contacts
(QPCs) realized in materials with anisotropic electron mass\, such as Si\,
may exhibit valley filter phenomena leading to extreme sensitivity to sin
gle donor occupancy\, and thus are of interest to measurement schemes for d
onor-based quantum information processing. To this end\, we have developed
ambipolar devices on a H-Si(111):Si(100)/SiO2 flip-chip assembly which util
ize in-plane\, degenerately doped n+ (P) and p+ (B) contacts to probe trans
port in a 2D electron system (2DES). In\naddition to providing electrostati
c isolation of carriers\, these p-type contacts can be used as lateral depl
etion gates to modulate the 2DES conductance\, and if extended to the nanos
cale can lead to 1D confinement and quantized conductance of the 2DES. In t
his talk\, I will describe our efforts to use a Ga focused-ion beam for dir
ect-write implant lithography to pattern QPCs and Ga nanowires on H-Si(111)
surfaces. I will present low temperature (4.2K) conductance data collected
on 30nm Ga nanowires to demonstrate their effectiveness as lateral depleti
on gates\, and discuss on going measurements to\nconfine and modulate the c
onductance of the 2DES using Ga QPCs.\n\n=================================\
n
LAST-MODIFIED:20170217T160749Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:2-20-2017Phys838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20190408T200000Z
DTEND:20190408T210000Z
DTSTAMP:20260416T023943Z
UID:15h4rosmgae7cukggsd8aahe7f@google.com
CREATED:20190213T194558Z
DESCRIPTION:Carr Lecture\, to be held in 1201 John S. Toll Physics Building
\n\nSpeaker: Gregory S. Boebinger\, U.S. National High Magnetic Field Labor
atory and Florida State University and the University of Florida\n\nTitle:
Using high magnetic fields to reveal critical behavior near optimum doping
in high-temperature superconductivity\n\nWe measure the electronic specific
heat in a series of Ba122 high-temperature superconductors. High magnetic
fields are used to suppress the superconducting state\, providing a direct
experimental determination of the density of electronic states that take pa
rt in superconductivity in these samples. We find that this density of stat
es is greatly enhanced as one approaches optimum doping\, evidencing increa
sed electronic correlations in more strongly superconducting samples. Indee
d\, the data extrapolate to imply a divergence precisely at optimum doping.
.
LAST-MODIFIED:20190404T202154Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Special Seminar: Gregory S. Boebinger
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20231204T210000Z
DTEND:20231204T220000Z
DTSTAMP:20260416T023943Z
UID:1eiib4eafmtu6b5ej3djm5jfh9@google.com
CREATED:20230821T193752Z
DESCRIPTION:Title: Acoustically-driven ferromagnetic resonance in
ferrimagnetic Y3Fe5O12 film with magnetic
anisotropy
Abstract: Spin wave devices seek to eff
iciently transport spin information via propagating waves of spin excitatio
ns in a lattice. Previous researchers have utilized the magnetoelastic effe
ct in order to launch spin waves via surface acoustic waves (SAWs)\, a phen
omenon known as acoustically-driven ferromagnetic resonance (ADFMR). While
these ADFMR studies have primarily focused on materials such as Ni\, such m
etals have short spin coherence lengths which limit their spintronics appli
cations. In this work\, we detect spin wave launching due to ADFMR in the f
errimagnetic insulator Y3Fe5O12\; (yttrium
iron garnet\, YIG)\, which has a longer coherence length. Interdigitated t
ransducers (IDTs) were used to send and receive bursts of SAWs through Y-cu
t LiNbO3 piezoelectric substrates. YIG thin films patterned betw
een these IDTs were able to partially absorb the SAWs under an applied fiel
d. This absorption demonstrates angle-dependence indicative of ADFMR and th
erefore spin wave launching. We also discuss the effect of in-plane magneti
c anisotropy on the ADFMR signature. These findings expand the possibilitie
s for spin wave devices to create low loss spintronics.
Ad
visor: Ichiro Takeuchi
LAST-MODIFIED:20231127T185700Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Thomas Wong
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221010T160000
DTEND;TZID=America/New_York:20221010T170000
DTSTAMP:20260416T023943Z
UID:0eh26dobde75db7glccvk5th0d_R20221003T200000@google.com
RECURRENCE-ID;TZID=America/New_York:20221010T160000
CREATED:20220822T163210Z
DESCRIPTION:Title: Room Temperature Coherent Si
ngle Photon Emitters in hBN
\;
Abstract: Single Photon Emi
tters(SPEs) are a critical component of many quantum technologies including
quantum network sand photonic quantum computation. These protocols often r
equire indistinguishable SPEs which can be identified by the Fourier transf
orm limited(FTL) linewidth of their emission spectrum. Previously\, FTL lin
ewidths in solid state emitters have only been observed at cryogenic temper
atures. Having a room temperature single photon source would dramatically r
educe the overhead needed for photonic quantum devices enabling everything
from wider quantum networks to integration of photonic quantum computers on
personal devices. Hexagonal boronnitride (hBN) is a wide bandgap\, insulat
ing\, exceptionally thermally and chemically robust material and can be int
egrated into a variety of photonic structures making it a perfect host mate
rial. Recently\, a new class of SPEs has been described in hBN which is the
first known SPE with FTL at room temperature. As of now\, the atomic struc
ture of this defect is unknown and the mechanism behind their unique proper
ties is an open question with implications for our understanding of 2D mate
rials as well as for use in quantum technologies. I will provide an overvie
w of the new class of SPEs described in hBN\, potential explanations for th
eir unusual properties\, and ideas for how to learn more about their struct
ure.
LAST-MODIFIED:20221010T160315Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Niko Reed
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20230417T200000Z
DTEND:20230417T210000Z
DTSTAMP:20260416T023943Z
UID:58ujndhq0vqgrum0vpteodh2br@google.com
CREATED:20230220T205729Z
DESCRIPTION:Title: Spintronics using spin-triplet superconductors
Ab
stract: Conventional superconductivity is mediated by singlet Cooper pairs
with antiparallel spins\, which are readily broken by magnetic interaction
via the orbital effect or the Zeeman effect1. For this reason\, superconduc
ting spintronic research has relied on random spin scattering or quasiparti
cles in proximitized superconductor/ferromagnet junctions\, rather than dir
ectly controlling the Cooper pair spins1–3. Recent discoveries of spin-trip
let superconductivity are expected to open a new route to employing spintro
nics in unprecedented time/length scales3\,4. In this talk\, we will discus
s superconducting spintronics based on spin-triplet superconductors. Backgr
ound and theoretical descriptions of the injection and detection of spin-po
larized carriers in superconductors will be first introduced\, followed by
literature surveys on spin-triplet superconductor spintronics. We will also
talk about ongoing research for spin injection and spin valve devices with
Py/BiPd heterostructures.
Advisor: Ichiro Takeuchi
In-Person Location: Toll Physics Room # 1201
Time: 4pm
-5:00pm
Also on Zoom: Meeting Link - https://umd
.zoom.us/j/97540478019
LAST-MODIFIED:20230411T195309Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Jihun Park
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170306T160000
DTEND;TZID=America/New_York:20170306T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170306T160000
CREATED:20170131T205940Z
DESCRIPTION:SPEAKER: Tarapada Sarkar\nAdvisor: R. Greene\n\nTITLE: "Elect
rical transport studies of electron doped superconductor La2-xCexCuO4"\n\n
ABSTRACT: I will discuss about normal state Hall coefficient and resistivi
ty measurements on La2-xCexCuO4 (LCCO) thin films as a function of doping a
nd temperature for magnetic fields up to 14T. A change in the sign of the l
ow temperature normal state Hall coefficient at 2K and nonlinear hall resis
tance as function of magnetic field suggests that the Fermi surface recon
structs at a critical doping of Ce= 0.14. This agrees with some prior high
field Hall Effect measurements of the LCCO system [K. Jin\, et al. PRB 78\
, 174521 (2008)]. In addition\, we find a large change in the carrier numbe
r at this doping\, similar to that seen in PCCO films [Y. Dagan\, et al. Ph
ys. Rev. Lett. 92\, 167001 (2004)] and hole-doped cuprates [S. Badoux\, et
al. Nature 531\, 210-214 (2016)]. \n\n=====================================
===\nSPEAKER: Rodney Snyder\nAdvisor: J. Williams\n\nTITLE: Josephson junc
tions of candidate topological crystalline insulator Pb1-xSnxTe\n\nABSTRACT
: Incorporating superconducting ordering through proximity effects in topo
logical states of matter offers potential routes to novel excitations with
properties beyond that of simple electrons. Topological crystalline insulat
ors TCI offer alternative routes to topological states of matter with surfa
ce states of distinct character to those in more common 3d topological insu
lators. We report on the fabrication Josephson junctions using MBE-grown ca
ndidate TCI material — Pb-doped SnTe — as weak links and characterize the d
epartures from conventional junctions using combined DC and RF techniques.
Opportunities to create junction weak links from materials possessing elect
ronic interactions will be discussed.
LAST-MODIFIED:20170301T193416Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20171211T160000
DTEND;TZID=America/New_York:20171211T170000
DTSTAMP:20260416T023943Z
UID:nfug9eack96h7gj383qiffh4ig@google.com
RECURRENCE-ID;TZID=America/New_York:20171211T160000
CREATED:20170417T185647Z
LAST-MODIFIED:20180117T182728Z
LOCATION:Room 1201 John S Toll Physics Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:838C Student Seminar (make up date)
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170904T160000
DTEND;TZID=America/New_York:20170904T170000
RRULE:FREQ=WEEKLY;UNTIL=20180212T045959Z;BYDAY=MO
EXDATE;TZID=America/New_York:20170904T160000
EXDATE;TZID=America/New_York:20171218T160000
EXDATE;TZID=America/New_York:20171225T160000
EXDATE;TZID=America/New_York:20180101T160000
EXDATE;TZID=America/New_York:20180108T160000
EXDATE;TZID=America/New_York:20180115T160000
EXDATE;TZID=America/New_York:20180122T160000
EXDATE;TZID=America/New_York:20180129T160000
EXDATE;TZID=America/New_York:20180205T160000
DTSTAMP:20260416T023943Z
UID:nfug9eack96h7gj383qiffh4ig@google.com
CREATED:20170417T185647Z
LAST-MODIFIED:20180117T182728Z
LOCATION:Room 1201 John S Toll Physics Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220425T160000
DTEND;TZID=America/New_York:20220425T173000
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs_R20220207T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20220425T160000
CREATED:20220121T185706Z
DESCRIPTION:Title: \;Dephasing Time T2 Enhance
ment of Two-Level Systems in Aluminum Superconducting Resonators
Abstract: \;Superconducting resonators are w
idely used in many applications such as qubit readout for quantum computing
applications\, and kinetic inductance detectors. These resonators are susc
eptible to numerous loss and noise mechanisms under microwave excitation\,
especially the dissipation due to non-equilibrium quasi-particles and two-l
evel systems (TLS)\, which can result in a decrease of the superconducting
intrinsic quality factor Qi in high quality superconducting resonators. Par
ticularly in the few-photon and low temperature regime\, TLS can become a d
ominant source for loss. In this study\, capacitively-coupled aluminum half
-wavelength resonators are investigated. An unusual increase of Qi(T) \
; with decreasing temperature is observed. This behavior is attributed to t
he increase of TLS dephasing timeT2 at low temperatures and powers. This T2
increase is consistent with other work on resonant frequency noise in reso
nators and measurements of individual TLS.
In-Person Location: Toll Physics Room # 1201
Ti
me: 4pm -5:30pm
Zoom LInk: \;https://umd.zoom.us/j/97265681008<
/a>
LAST-MODIFIED:20220420T142251Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Jingnan Cai
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220131T160000
DTEND;TZID=America/New_York:20220131T173000
RRULE:FREQ=WEEKLY;WKST=SU;UNTIL=20220207T045959Z;BYDAY=MO
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs@google.com
CREATED:20220121T185706Z
DESCRIPTION:Introduction: PHYS838C Seminar - Sprin
g 2022
While we will continue to use
this course primarily as a means for students and postdocs to both \;<
b>practice scientific presentations \;and \;share and discus
s their research projects \;with others in the center\, we will als
o continue to include "CAREER" talks for the benefit of junior researchers.
For these\, we will bring in \;prominent scientists from academia\,
national labs\, funding agencies and industry \;to talk about thei
r career path\, give advice and answer any questions students and postdocs
may have. This will be a great opportunity for juniors to ponder career cho
ices and better understand the road ahead of them!
In-Person Location: Toll Physics Room # 1201
<
u>Time: 4pm -5:30pm
Zoom LInk:&n
bsp\;https://umd.zoom.us/j/9726
5681008
LAST-MODIFIED:20220128T180601Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar:
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150223T160000
DTEND;TZID=America/New_York:20150223T175000
DTSTAMP:20260416T023943Z
UID:gr7ovnvmgo3so00u0full3btg8@google.com
RECURRENCE-ID;TZID=America/New_York:20150216T160000
CREATED:20150127T161958Z
DESCRIPTION:Speaker: Kefeng Wang (Paglione)\nTitle: Giant magnetoresistanc
e and band structure of topological semimetal RhSb3\n\nAbstract: Recently m
aterials with skutterudite structure such as CoSb were predicted to provide
a promising platform for the realization of new topological materials such
as topological insulators and Dirac-Weyl semimetals. Here we report a deta
iled study of the electronic structure and magnetotransport properties of h
igh quality RhSb3 single crystals. \nFirst-principles electronic structure
calculations reveal a highly dispersive band with Sb-p and Rh-3d weight tha
t shows apparent band inversion. Inclusion of spin-orbit coupling leaves th
e Fermi level pinned to a doublet\, indicating a topological semimetal. Our
synthesized high-quality single crystals show typical metallic behavior bu
t with very small residual resistivity ratio\, a sign of semimetal behavior
\, in zero field. We will present magnetotrasport data that exhibits a very
large magnetoresistance that hints of a very sensitive evolution of electr
onic properties and Dirac-like spectrum.\n\nSpeaker: Wanting Liao (Dreyer/
Lobb/Wellstood)\nTitle: Millikelvin Dual-Tip Scanning Tunneling Microscope\
n\nAbstract: We have built a dual tip scanning tunneling microscope (STM) [
1] with two niobium tips connected by niobium foil made by laser cutting. B
oth tips could be Josephson-coupled to a superconducting surface sample to
form an asymmetric SQUID loop. Our scheme involves holding one of the tips
fixed as a reference junction while the other tip is scanned to image the g
auge-invariant phase of superconductors at the atomic scale [2]. The micros
cope has worked at millikelvin temperature with two independent tips and we
are testing the connected-tips setup at room temperature.\n[1] A. Roychowd
hury\, et al.\, Rev. Sci. Inst. 85\, 04.706(2014)\n[2] “Asymmetric supercon
ducting quantum interference devices for suppression of phase diffusion in
small Josephson junctions”\, D. F. Sullivan\, et al.\, J. Appl. Phys. 113\,
183905 (2013)\n
LAST-MODIFIED:20150504T213425Z
LOCATION:Toll 1201
SEQUENCE:4
STATUS:CONFIRMED
SUMMARY:PHYS 838C - CNAM Seminar Series
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20151116T160000
DTEND;TZID=America/New_York:20151116T175000
DTSTAMP:20260416T023943Z
UID:lbg0jjlt95qgb660qgasop9f1k@google.com
RECURRENCE-ID;TZID=America/New_York:20151116T160000
CREATED:20150827T172216Z
DESCRIPTION:SPEAKER: Shavindra Premaratne\n\nTITLE: Fock State Generator\n\
nABSTRACT: Using a single junction Al/AlOx/Al transmon qubit coupled to a
superconducting Aluminum cavity (at a temperature 15 mK)\, we have used a R
aman technique to produce a single Fock state in the cavity. The technique
requires 3 microwave tones to drive the system from the ground state of the
cavity/qubit system. We achieve an experimental fidelity of the final Fock
state of around 90%\, limited by thermal photons in the cavity and by deca
y during the operation time. Using this technique\, we have also generated
an arbitrary superposition of Fock states and a superposition of qubit and
cavity states. Results\, simulations and applications of this technique wil
l be discussed.\n\nAdvisors: Dr. Ben Palmer\, Prof. Fred Wellstood
LAST-MODIFIED:20240912T112346Z
LOCATION:1201 Physics John S Toll Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C: Shavi Premaratne
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200210T160000
DTEND;TZID=America/New_York:20200210T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20200210T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker: Wen-Chen Lin\n\nTitle: Phase Diagram of Spin Triplet S
uperconductor UTe2 Under Pressure and Magnetic Field\n\nAbstract: The heavy
fermion superconductor UTe2 has recently drawn much attention due to sever
al exotic properties. It exhibits two reentrant superconducting states unde
r extremely high magnetic fields that appear correlated with ferromagnetic
interactions\, and has been proposed as a candidate three-dimensional topol
ogical superconductor. Here\, we report the details of the field-temperatur
e-pressure phase diagram of UTe2 under pressures up to 18.8kbar and high ma
gnetic fields. Electrical resistivity and tunnel diode oscillator (TDO) mea
surements were performed under external magnetic field along the crystallog
raphic b axis (hard axis)\, revealing a systematic progression of the super
conducting and field-polarized phases that have relations to those observed
at ambient pressure. We will discuss our observations and their relevance
on the interplay between ferromagnetism and superconductivity in this rich
system.
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20161003T160000
DTEND;TZID=America/New_York:20161003T180000
DTSTAMP:20260416T023943Z
UID:f281rippqjv8l5kfem2eqqd5gc@google.com
RECURRENCE-ID;TZID=America/New_York:20161003T160000
CREATED:20160907T190615Z
DESCRIPTION:SPEAKER: Wan-Ting Liao\nAdvisor: Dreyer/Lobb/Wellstood\n\nTITL
E: How to simultaneously scan connected tips in a dual-tip STM\n\nABSTRACT:
Starting with a dual independent-tip scanning tunneling microscope (STM)
design\, we have connected the two tips by a short (∼3 mm) flexible Nb foil
strip that was patterned by a laser.To enable simultaneous imaging with bot
h tips\, we move both tips to within tunneling distance of a surface and mo
dulate one tip's z-piezo at ∼ 5 kHz and the other at∼10 kHz. The resulting
combined tunneling current from the system has modulation at both frequenci
es\, which we detect using two lock-in amplifiers. The two outputs (dI/dZ 1
and dI/dZ 2) are fed back to individual STM electronic controllers to allow
simultaneous topographic imaging using both tips. Our goal is to operate t
his dual-tip STM at 30 mK on a superconducting sample so that the device fo
rms a scanning superconducting quantum interference device (SQUID). Holding
one of the tips fixed as a reference junction\, the other tip will be scann
ed to image the gauge-invariant phase difference of a superconductor at the
atomic scale.\n\n=========================\nSPEAKER: Nat Steinsultz\nAdvis
or: Min Ouyang\n\nTITLE: Nitrogen Vacancy Centers as Probes of Nanoscale
Magnetism\n\nABSTRACT: I will discuss the different ways in which the Nitro
gen-Vacancy defect hosted in nanodiamonds can be used to probe different fe
atures of magnetic fields on the nanoscale. I will then discuss how these c
an be employed to investigate the magnetic behavior of superparamagnetic ir
on oxide nanoparticles grown on the surface of nanodiamonds in a hybrid nan
o-structure.\n\n
LAST-MODIFIED:20161003T050422Z
LOCATION:Room 1201\, John S Toll Physics Bldg.
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20180226T160000
DTEND;TZID=America/New_York:20180226T170000
DTSTAMP:20260416T023943Z
UID:3kdb9qivnhpd74jjv5jupneh2u_R20180129T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20180226T160000
CREATED:20180117T182452Z
DESCRIPTION:=======================
=====================================
Speaker: \; Snyder\, Rodney (
Williams)
Title:Josephson Junctions
with Weak Links of Topological Crystalline Insulators
Abstract
:We report on the fabrication of Josephson ju
nctions using the topological crystalline insulator Pb0.5Sn0.5Te \;as the weak link. The properties of these junctions are characteri
zed and compared to those fabricated with weak links of PbTe\, a similar ma
terial yet topologically trivial. Most striking is the difference in the AC
Josephson effect: junctions made with \;Pb0.5Sn0.5Te
\;exhibit rich subharmonic structure consistent wit
h a skewed current-phase relation. This structure is absent in junctions fa
bricated from PbTe. A discussion is given on the origin of this effect as a
n indication of novel behavior arising from the topologically nontrivial su
rface state. \; Finally some further experiments that will be performed
will be outlined as well as preliminary \;results will be discussed.&n
bsp\; \;
==============
=============================================
LAST-MODIFIED:20190109T201341Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20201207T210000Z
DTEND:20201207T220000Z
DTSTAMP:20260416T023943Z
UID:787bjfjs94399aiq6rgb0ckmoi@google.com
CREATED:20201119T155957Z
DESCRIPTION:Speaker: Dr. Todd Brintlinger\, \;U.S. Naval Res
earch Laboratory \; \;
Title: Career Speaker Series: \;A Car
eer in Physics at a Government Laboratory
Physics degree holders
are highly employable in both the private and public sectors. However\, stu
dents and early career scientists are often unaware of the types of career
paths available to them. This talk will provide data on the number of physi
cs degree holders and where they typically find employment\, give examples
of common career paths\, and provide guidance on\, and highlight career res
ources useful for\, exploring options and searching for jobs. \; While
focusing specifically on physics\, much of the same information is applicab
le for related disciplines\, especially materials science. \; I will de
scribe my own career path\, starting here at the University of Maryland and
continuing at the U.S. Naval Research Laboratory\, the corporate laborator
y for the U.S. Navy\, where I have used physics to study systems spanning m
any length and energy scales in the Materials Science and Technology Divisi
on.
DISTRIBUTION A: \; Approved for public release\, distribu
tion is unlimited.
Zoom
Link \; &\; \; \;Log In Information
Meeting ID: 91
1 9803 7643 \;
Password:558484 \;
LAST-MODIFIED:20201211T175514Z
LOCATION:Zoom
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar CAREER Speaker: Dr. Todd Brintlinger\, U.S. Nava
l Research Laboratory
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20260223T210000Z
DTEND:20260223T220000Z
DTSTAMP:20260416T023943Z
UID:11jnqdpg243dak7oe2el7b2p0k@google.com
CREATED:20260121T191119Z
DESCRIPTION:
Title: YAuPb - The first in a new Branch of the Half Heusle
r Family
Abstract: The noncentrosymmetric half-Heusler crystal struc
ture holds a wide variety of materials with unique phenomena\, including un
conventional superconductivity\, nontrivial topological band structu
res\, and magnetic order. In this impressive family of materials we introdu
ce a new superconducting member\, YAuPb. The RAuPb branch of the half Heusl
ers is relatively unstudied leaving a new avenue for crystal growth and dis
covery. In this talk\, we shall go over the synthesis of this novel materi
al as well as a wide range of properties that it has displayed. Of these pr
operties we will focus on its unique normal state transport behavior\, its
superconductivity transition temperature\, its enhancement of magnetoresist
ance near 5K\, and the temperature evolution of its carrier density.
Advisor: Paglione
LAST-MODIFIED:20260222T172133Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:2
STATUS:CONFIRMED
SUMMARY: PHYS838C Seminar: Carsyn Lee Mueller
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150914T160000
DTEND;TZID=America/New_York:20150914T175000
RRULE:FREQ=WEEKLY;UNTIL=20151207T210000Z;BYDAY=MO
EXDATE;TZID=America/New_York:20151012T160000
EXDATE;TZID=America/New_York:20151019T160000
EXDATE;TZID=America/New_York:20151123T160000
DTSTAMP:20260416T023943Z
UID:lbg0jjlt95qgb660qgasop9f1k@google.com
CREATED:20150827T172216Z
LAST-MODIFIED:20240912T112346Z
LOCATION:1201 Physics
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C: Damieng Zhang and Cody Ballard
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20180423T160000
DTEND;TZID=America/New_York:20180423T170000
DTSTAMP:20260416T023943Z
UID:3kdb9qivnhpd74jjv5jupneh2u_R20180129T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20180423T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker: \; Liao\, WanTing <
/span> (Dreyer/Wellstood)
Title: Inhomogeneity of the gap from TiN films studied by l
ow-temperature STM (Scanning Tunneling Microscopy)
\;
Abstract: \; Titanium Nitride films
with high kinetic inductance show great promise for use in superconducting
qubits and resonators. The magnitude of the kinetic inductance and the loss
in the films depend crucially on the preparation conditions and resulting
film morphology. Here we report STM measurements done at 400 mK on a 20 nm-
thick and a 40 nm thick oxygen treated film. \;The super
conducting gap can be observed after gentle sputter cleaning of the surface
\, with the gap varying from grain to grain by more than 20%. We will prese
nt spatially resolved superconducting gap maps both for 20 nm thick and 40
nm thick films\, examine the correlation between the surface topography and
gap\, and discuss some of the implications of these results for supercondu
cting qubits.
=======================================
======
Speaker: \; Robertson\, Luke (Kane)
Title: Non-invasive SOI gating of 2D ele
ctron systems on pristine hydrogen-terminated Si surfaces
Abstract:&
nbsp\; Silicon has a variety of surface terminations in which surfaces stat
es are passivated and where 2D electron or hole surface accumulation layers
are possible through electrostatic gating. Because of the simplicity and h
igh degree of perfection\, we use a wet chemical treatment to terminate Si(
111) surfaces with hydrogen and have developed techniques to probe 2D trans
port on these passivated surfaces. While other chemical terminations of dif
ferent Si surfaces exist (e.g. Cl\, Br\, I)\, we have focused exclusively o
n H-Si(111)\, but are in process of extending our study to include H-Si(100
) surfaces as their 2-fold valley degeneracy are more favorable platforms f
or quantum information processing. We are now developing techniques to prob
e pristine hydrogen-terminated Si(111) and Si(100) surfaces using a non-inv
asive SOI flip-chip gating method in which all device fabrication is perfor
med on the SOI piece. Extremely high mobilities in excess of 300\,000 cm2/V
s have been demonstrated in our devices\, and further refinement of techniq
ues to preserve the pristine nature of the terminated Si surfaces is expect
ed to yield even higher mobilities. Architecture details and ohmic contact
tests will be presented as well as ongoing low temperature device character
ization measurements.
==============================================
LAST-MODIFIED:20190109T201341Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20200928T200000Z
DTEND:20200928T213000Z
DTSTAMP:20260416T023943Z
UID:43ke56ntdmvka0nvbv6ra8s5ju@google.com
CREATED:20200909T165039Z
DESCRIPTION:Speaker: Dr. Nicholas Butch
Title: Career Speaker Series
Dr. Ni
cholas Butch will be discussing his career trajectory from the perspective
of working for a national lab.
The Career Speaker Series is meant
to give advice to junior scientist on what their choices are\, how life wor
ks after grad school\, what scientific careers are out there.
Zoom Link &am
p\; Log In Information
Meeting ID: 911 9803 7643
Pa
ssword:558484
LAST-MODIFIED:20201014T144328Z
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar CAREER Speaker: Nicholas Butch\, NIST
TRANSP:TRANSPARENT
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220207T160000
DTEND;TZID=America/New_York:20220207T173000
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs_R20220207T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20220207T160000
CREATED:20220121T185706Z
DESCRIPTION:
Title: Evolution of Charge Order in Ba(1-x)SrxAl
4
Abstract: The BaAl4 type structure hosts a variety of interesting and
exotic properties. Recent results have shown an emergence of CDW order in S
rAl4 at 243K\, together with a hysteretic structural transition at 87K that
is thought to be a structural transition to a monoclinic system. The tetra
gonal structure of BaAl4 has also recently been shown to have topologically
non-trivial bands and has lattice parameters very close to SrAl4. In order
to study the interplay between these features we have done a chemical subs
titution study to track the reported transitions. We have performed electri
cal resistivity measurements\, along with x-ray and neutron scattering on t
he Ba(1-x)SrxAl4 family. We show a suppression of the CDW order with increa
sed Ba substitution. Neutron scattering and x-ray measurements show the nat
ure of the CDW.
In-Person Locati
on: Toll Physics Room # 1201
Time: 4pm -5:30pm
<
u>
Zoom LInk: \;https://umd.zoom.us/j/97265681008
LAST-MODIFIED:20220204T165627Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Prathum Saraf
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210920T160000
DTEND;TZID=America/New_York:20210920T173000
DTSTAMP:20260416T023943Z
UID:0bdfeomp1fm5g8gcuh328k3ecm@google.com
RECURRENCE-ID;TZID=America/New_York:20210920T160000
CREATED:20210816T160956Z
DESCRIPTION:Speaker 1: Jihun Park \;
Advisor: \; Ichiro Takeuchi
Title: Combinatorial Approach For Mapping Superconducting Phase Diagram
In The Bi–Ni Binary System
Abstract: \;Abstract: \;The Bi–Ni
binary system is an intriguing material platform that encompasses two inco
mpatible phases \;– a ferromagnetic phase (Ni) and an intermetallic sup
erconducting phase (BiNi and Bi3Ni). In particular\, the Bi3Ni phase is kno
wn to \;evolve spontaneously at the interface of Bi-rich Bi/Ni bilayers
\, which may exhibit \;p-wave spin-triplet superconductivity when in cl
ose proximity to the ferromagnetic \;Ni layer1–3. However\, the role of
excessive Bi in this system \;is still a question mark regardless of i
ts significance in superconductivity.In this talk\, we will discuss the
superconducting phase diagram in the Bi–Ni binary system obtained via a com
binatorial approach. The phase diagram reveals that the \;monoclinic Bi
Ni phase observed is not superconducting. Also\, Bi inclusion is \;iden
tified to enhance the superconducting critical temperature of Bi3Ni\, thoug
h acting as an impure phase in the system and thereby reducing superconduct
ing coherence length. Remarkably\, the superconductivity of Bi3Ni remains r
obust even in the excessively Bi-rich stoichiometry. These findings possibl
y provide clues for the role of Bi in the Bi–Ni superconducting system.
[1] P. Chauhan \;et al. Phys. Rev. Lett. \;122\, 0
17002 (2019).
[2] M. Vaughan \;et al. Phys. Rev. Res. \;<
b>2\, 013270 (2020).
[3] X. Shang \;et al. Phys. Rev. B&n
bsp\;101\, 174514 (2020).
Note: there will NOT be receptions
prior to the talk until further notice.
LAST-MODIFIED:20220601T082228Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Jihun Park
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20150209T160000
DTEND;TZID=America/New_York:20150209T175000
DTSTAMP:20260416T023943Z
UID:gr7ovnvmgo3so00u0full3btg8@google.com
RECURRENCE-ID;TZID=America/New_York:20150209T160000
CREATED:20150127T161958Z
DESCRIPTION:Speaker: I-Lin Liu (Butch)\nTitle: Magnetism and Structure in
Fe1:1-xNixTe\nAbstract: We present magnetic and structural transitions of i
ron telluride doped with different concentrations of nickel. There are two
magnetic transitions evident in magnetic susceptibility. The higher transit
ion temperature is at 125 K\, caused by the phase transition of iron oxide
impurities. Moreover\, the lower temperature magnetic transition\, associat
ed with an orthorhombic distortion\, decreases from 55 to 25 K when the con
centration of nickel increases. The results show that Ni substitution suppr
esses the monoclinic distortion and long range magnetic order\, which means
that iron telluride doped with nickel is a promising material for the stud
y of superconductivity under pressure.\n\n
LAST-MODIFIED:20150504T213425Z
LOCATION:Toll 1201
SEQUENCE:3
STATUS:CONFIRMED
SUMMARY:PHYS 838C - CNAM Seminar Series
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20250929T200000Z
DTEND:20250929T210000Z
DTSTAMP:20260416T023943Z
UID:3rr229vqo63shvti9id1o7a7ej@google.com
CREATED:20250825T190742Z
DESCRIPTION:Title: Universal Frequency Correlations and Recurrence St
atistics of Complex Impedance Matrices
Abstr
act: Linear electromagnetic wave scattering systems can be characterized by
an impedance matrix that relates the voltages and currents at the ports of
the system. When the system size becomes greater than the wavelength of th
e fields involved\, the impedance matrix becomes a complicated function of
the details of the system\, in which case a statistical model\, such as the
Random Coupling Model (RCM) becomes useful. The statistics of the elements
of the RCM impedance matrix depend on the excitation frequency\, the spect
ral density of the modes of the enclosed system volume\, the average loss f
actor (Q^-1) of the system\, and the properties of the coupling ports as gi
ven by their radiation impedances. In this talk\, properties of the element
s of impedance matrices are explored numerically and experimentally. These
include the two point frequency correlation functions for the complex imped
ance of elements and the expected difference in frequencies between which i
mpedance values are approximately repeated. Universal scaling arguments are
then given for these quantities\, hence these results are generic for all
sufficiently complicated scattering systems\, including acoustic and optica
l systems. The experimental data presented in this talk come from microwave
graphs\, billiards\, and three-dimensional cavities with embedded tunable
perturbers such as metasurfaces. The data is found to be in generally good
agreement with the predictions for the two point frequency correlations and
the frequency interval for successive repetitions of impedance matrix elem
ents values.
Advisor: Steve Anlage
LAST-MODIFIED:20250915T174246Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Nadav Shaibe
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20251006T200000Z
DTEND:20251006T210000Z
DTSTAMP:20260416T023943Z
UID:456lu1f3fcercmo4qui6179bph@google.com
CREATED:20250825T190809Z
LAST-MODIFIED:20250826T173433Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Arthur Carlton-Jones
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170508T160000
DTEND;TZID=America/New_York:20170508T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170508T160000
CREATED:20170131T205940Z
DESCRIPTION:SPEAKER: Yangang Liang\nAdvisor: I. Takeuchi\n\nTITLE: W-dope
d VO2 thin films prepared by a combinatorial method for Li-ion battery appl
ications\n\nABSTRACT: Vanadium dioxide (VO2) has been extensively studied
due to its fully reversible first-order metal-insulator transition (MIT) as
sociated with a structural phase transition at about 68 °C. For potential w
ider applications in rechargeable lithium batteries\, we systematically stu
died the structural phase transition and the electronic properties of compo
sition spread V1-xWxO2 (0 ≤ x ≤ 0.037) thin films fabricated on silicon (00
1) and c-cut sapphire substrates through combinatorial pulsed laser deposit
ion of a VO2 target and a WO2 target. Electrical transport results show tha
t both the phase transition temperature and the width of the hysteresis loo
p decrease with the increasing of the concentration of tungsten. Especially
\, epitaxial V1-xWxO2 films fabricated on c-cut sapphire substrates show na
rrower hysteresis loop compared to textured V1-xWxO2 films fabricated on Si
(100) substrates. In addition\, we also studied the effects of substrate a
nd temperature on the crystal structures of V1-xWxO2. Moreover\, their pot
ential use as cathodes materials for rechargeable lithium batteries is inve
stigated.\n\n=================================================\n\nSPEAKER:
Pampa Sarkar\nAdvisor: R. Greene\n\nTITLE: Nernst effect in electron doped
cuprate superconductor La2-xCexCuO4\n\nABSTRACT: For nearly three decades\
, high TC cuprate superconductors have gained much scientific attention to
understand the pairing mechanism of superconductivity. We will discuss abou
t the Nernst signal measurements of epitaxial thin film of La2-xCexCuO4 fro
m underdoped (x = 0.08) to overdoped (x = 0.16) samples for a wide range of
temperature above TC. These measurements will be related to our present un
derstanding of the normal state and superconductivity in the cuprates. \n\n
LAST-MODIFIED:20170424T171131Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211025T160000
DTEND;TZID=America/New_York:20211025T173000
DTSTAMP:20260416T023943Z
UID:0bdfeomp1fm5g8gcuh328k3ecm@google.com
RECURRENCE-ID;TZID=America/New_York:20211025T160000
CREATED:20210816T160956Z
DESCRIPTION:Speaker: \; Julia Catherine Sell \;
Advisor: \;
Mohammad HafeziTitle: Magneto-Optical Measurements of Charged and Neu
tral Excited-States in Monolayer WSe2
Abstract: Monolayer semiconduc
tor transition metal dichalcogenides (TMDs) have attracted significantatten
tion in the last decade due to their unique optical properties. Similar to
graphene\, but with a threelayer (staggered) honeycomb lattice\, TMDs host
direct-gap transitions at their ±K valleys that exhibitcircular-dichroism d
ue to their finite Berry curvature. The reduced dimensionality of materials
in thissystem\, coupled with techniques like hexagonal boron nitride (hBN)
encapsulation\, lead to enhancedCoulomb interaction and extremely tightly
bound excitons EB ≈300-500meV. This results in asemiconductor platform wher
e many quasiparticle states\, including multi-particle states like trions\,
biexcitons (both neutral and charged)\, and most recently exciton-polarons
can all coexist with distinctenergetic signatures. The extremely tight bind
ing also allows observation of excited versions of theseparticles\, as part
of the Rydberg series in TMDs.Because of the large number of quasiparticle
species that can be observed simultaneously\, themagnetic field dependence
of these states has become an important tool in understanding and reliably
identifying each species. However\, over time there have been a significant
number of reports in theliterature that observe magnetic behavior that div
erges from the single-particle model. These reportshave led to an emerging
many-body interpretation that can reconcile the broad range of results. In
ourwork\, we aim to further contribute to the understanding of this interac
tion in an excited regime. Usingphotoluminescence excitation (PLE)\, we con
firm the existence of a charged Rydberg state in WSe2.Further\, we study th
e response of this state with magnetic field for the first time. These meas
urementsshine light on the nature of excited states and show that many-body
interaction observed in the groundstate remains a valid interpretation in
the excited regime as well.
Note: there will NOT be receptions prio
r to the talk until further notice.
LAST-MODIFIED:20220601T082238Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Julia Sell
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20230410T200000Z
DTEND:20230410T210000Z
DTSTAMP:20260416T023943Z
UID:5eeij0aiqcvuegb517cnq801bd@google.com
CREATED:20230216T171058Z
LAST-MODIFIED:20230410T183826Z
LOCATION:Toll Physics Rm # 1201
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: ///// Cancelled/////
TRANSP:TRANSPARENT
END:VEVENT
BEGIN:VEVENT
DTSTART:20231002T200000Z
DTEND:20231002T210000Z
DTSTAMP:20260416T023943Z
UID:4f2pnq8kfo73n67i9111b5bkto@google.com
CREATED:20230821T192659Z
DESCRIPTION:Title: Measurement of Non-equilibrium Quasipart
icle Tunneling Rates in
Superconducting Qubits
Abstract: The origin of non-equilibrium quasiparticles (
QPs) in superconducting devices operating at very low temperature of 20 mK
has been a mystery for decades. Specifically\, for superconducting quantum
bits (qubits)\, a QP that tunnels across the Josephson junction (JJ) can in
duce energy relaxation and dephasing\, therefore limiting the coherence of
the device. Understanding the sources and dynamics of QPs in these devices
is crucial to evaluate and improve the performance of the devices. Here\, a
n experiment that aims to monitor individual QP tunneling events in the tim
e domain is performed. By applying a Ramsey-like pulse sequence\, I extract
the time scale for a single QP tunneling through the JJ on transmon qubits
which have a measurable amount of charge dispersion and measuring the qubi
t state in single shots with a high fidelity. By measuring the QP tunneling
rates in qubits of floating and grounded styles with aluminum and tantalum
ground planes\, I compare the impact of different qubit designs and materi
als on QP dynamics.
Location: Toll Physics Room # 1201
Time: 4pm
LAST-MODIFIED:20230926T002934Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Yi-Hsiang Huang
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20161024T160000
DTEND;TZID=America/New_York:20161024T180000
DTSTAMP:20260416T023943Z
UID:f281rippqjv8l5kfem2eqqd5gc@google.com
RECURRENCE-ID;TZID=America/New_York:20161024T160000
CREATED:20160907T190615Z
DESCRIPTION:SPEAKER: Lance Boyer\nAdvisor: Victor Yakovenko\n\nTITLE: A Mod
el for Metastable Magnetism in URu2Si2\n\nABSTRACT: We propose an explanat
ion for the experiment by Schemm et al. Phys. Rev. B 91\, 140506 (2015) in
which a polar Kerr effect (PKE) was observed in the Hidden-Order (HO) phase
of URu$_2$Si$_2$. This experiment detected a PKE on warm-up in the HO phas
e only if a magnetic training field was present on cool down through the HO
phase transition. Using the free energy of a Landau-Ginzburg model\, we sh
ow how a thermodynamically metastable ferromagnetic state can give rise to
the PKE even if the underlying HO respects time-reversal symmetry. We also
specify an experimental probe for the metastable state.\n\n================
===============================\n\n\n
LAST-MODIFIED:20161010T172631Z
LOCATION:Room 1201\, John S Toll Physics Bldg.
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170911T160000
DTEND;TZID=America/New_York:20170911T170000
DTSTAMP:20260416T023943Z
UID:nfug9eack96h7gj383qiffh4ig@google.com
RECURRENCE-ID;TZID=America/New_York:20170911T160000
CREATED:20170417T185647Z
DESCRIPTION:SPEAKER: Hyunsoo Kim (Paglione)\n\nTITLE: Electronic structure
of YPtBi: transport study\n\nABSTRACT: Noncentrosymmetric topological semim
etal YPtBi has been considered as the first realization of high spin Cooper
pairing with mixed singlet and septet states. Determination of exact super
conducting pairing states requires a detailed knowledge of band structure a
s well as Fermi surface. However\, structure of Fermi surface of YPtBi is n
ot fully known due to experimental limitations. In addition\, theoretical b
and structure near the chemical potential has been controversial. The measu
rement of electrical transport is among useful probes to study the electron
ic structure. In this talk\, the electronic structure of YPtBi will be disc
ussed based on electrical transport measurements including resistivity and
Hall effect in order to shed light on the current issues of electronic stru
cture of YPtBi. \n\n=============================\nSPEAKER: Peng Xu (Osborn
)\n\nTITLE: Thickness Dependent Quality Factor in O2 plasma pretreated TiN
film\n\nABSTRACT Superconducting titanium nitride (TiN) films are used in q
uantum computing devices because they can exhibit low microwave loss and hi
gh kinetic conductance. One of the major sources of loss is due to Two Leve
l Systems (TLS) defects present at the interface between TiN and the substr
ate. Thus we pre-treated the substrate with a number of different functiona
lizations including O2\, argon and C4H4 at two different film thicknesses (
25nm and 50nm). Unexpectedly\, we found a thickness dependence of internal
quality factor for the pre-treated O2 films. An order of magnitude shift in
internal quality factor (Qi) is shown in the experimental transmission dat
a of the coplanar waveguide resonators. The XPS\, XRD\, and SIMS show that
the growth\, grain size and structure of film have been modified in the 25n
m film because of the oxygen pretreatment. We also see a difference in the
temperature dependence where quasiparticle seem to be already present in th
e thinner O2 film at low temperatures. This deviation could be the result o
f a transition to a highly disordered superconductor where the mean free pa
th\, l\, is smaller than coherence length\, L. A modified Mattis Bardeen th
eory including quasiparticle scattering fits the temperature dependence dat
a well. \n
LAST-MODIFIED:20180117T182728Z
LOCATION:Room 1201 John S Toll Physics Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220328T160000
DTEND;TZID=America/New_York:20220328T173000
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs_R20220207T210000@google.com
RECURRENCE-ID;TZID=America/New_York:20220328T160000
CREATED:20220121T185706Z
DESCRIPTION:Title: QuasiparticleTunneling Suppression in Gap-
Engineered Transmons
Abstract: For many superconducting qubits\,
non-equilibrium quasiparticlestunneling across the Josephson junction is su
spected to be one of the dominantsources of energy relaxation. This loss me
chanism is expected to besuppressed \;in devices with junctions that ar
e made from electrodes with sufficientlydifferent superconducting gaps [1].
We have designed and fabricated anasymmetric Al/AlOx/Al/Ti transmon couple
d to a 3D Al cavity. To do this\, wedeposited one pure Al electrode\, oxidi
zed it\, and then deposited an Al/Tibilayer as the counter-electrode. This
process forms a standard AlOx tunnelbarrier\, but gives a ~100 μeV differen
ce in superconducting gaps due to the Tiproximitizing the Al of the top lay
er. Fabrication of these devices\, Giaevertunneling measurements of the sma
ll Al/AlOx/Al/Ti junction\, as well ascoherence measurements of the device
will be discussed.
[1] Zhang\, PhD Thesis DOI: 10.13016/c516-gizd (2
020)
In-Person Location: Toll Ph
ysics Room # 1201
Time: 4pm -5:30pm
<
u>
Zoom LInk: \;https://umd.zoom.us/j/97265681008
LAST-MODIFIED:20220324T163537Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Zachary Steffen
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211115T160000
DTEND;TZID=America/New_York:20211115T173000
DTSTAMP:20260416T023943Z
UID:0bdfeomp1fm5g8gcuh328k3ecm@google.com
RECURRENCE-ID;TZID=America/New_York:20211115T160000
CREATED:20210816T160956Z
DESCRIPTION:Speaker 1: Arthur Carlton Jones
Title: Determining
UTe2 surface impedance through microwave resonance measurements
\;
Abstract: The complex surface impedance of a superconductor p
rovides many insights into its properties\, such as the pairing mechanism\,
super- and normal-fluid responses\, and possibly it’s topological properti
es. We explore the surface impedance of a UTe2 single crystal as
a function of temperature using resonant cavity measurements for a variety
of microwave-frequency modes. By determining the resonant frequency and qu
ality factor over a range of temperatures\, we reconstruct the surface impe
dance of the sample. We match the behavior of the resistance and reactance
in the normal state to their expected behavior\, determined by the normal s
tate resistivity. \;Since UTe2 is anisotropic\, we take a l
inear combination of the losses corresponding to each crystallographic dire
ction to do this fitting. Through this method\, the anisotropic nature of U
Te2 allows us to determine the combination of crystallographic d
irections excited in each resonant mode. We present the results of the anis
otropic surface impedance temperature dependence in the superconducting and
normal states\, as well as additional quantities which can be determined f
rom the surface impedance including complex conductivity\, penetration dept
h\, and quasiparticle scattering time. We relate the results to topics of c
urrent interest in this unique material.
Advisor: \; Steven Anla
ge \;
Speaker 2: Raymond Mencia
Title: Blo
chnium: A \; \;flux-insensitive qubit with flux-tunable interaction
s
Abstract: \;We introduce a flux-like qubit\, nicknamed 'blochn
ium'\, whose 0-1 transition frequency is nearly insensitive to the external
flux bias \;and is dual to transmon. Blochnium is created by shunting
a small Josephson junction with a \;hyperinductance\, that is -- a maxi
mal per-unit-length inductance that has minimal stray capacitance and is pr
obably the highest impedance electromagnetic structure available today (Z&n
bsp\; >\; 200 kOhms). To achieve such inductances\, we release the entire
circuit from the high dielectric substrate and suspend it almost entirely
in vacuum. The qubit’s spectrum reveals a 0-1 flux dispersion on the order
of a hundred MHz which becomes exponentially suppressed when decreasing the
ratio EL/EC providing protection against 1/f flux noise. However\, the hig
her transitions remain flux-sensitive allowing for multi-qubit operations.
We report on recent coherence properties of blochnium with varying device d
esign and etching techniques.
Advisor: Vladimir Manucharyan \;
Location: Phys Toll Rm#1201
Seminar also on ZOOM: \; \
;https://umd.zoom.us/j/97540478
019
LAST-MODIFIED:20220601T082232Z
LOCATION:Toll Physics Rm 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Arthur Carlton Jones/Raymond Mencia
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200302T160000
DTEND;TZID=America/New_York:20200302T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20200302T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker:
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C: No Class
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20250505T200000Z
DTEND:20250505T210000Z
DTSTAMP:20260416T023943Z
UID:15iqu2i2qqjvtorhc6p72ttv9q@google.com
CREATED:20250130T172226Z
DESCRIPTION:Title: Coherence Measurements of Transmon Qubits w
ith In-Situ Patches
In the fabrication
of transmon qubits\, an aggressive ion-mill step is required to remove the
native oxide on the already present shunting capacitor and additively conn
ect the deposited Al/AlOx/Al Josephson junction. To prevent ion milling und
erneath the junction\, a potential source of loss for the qubit\,[1] Osman
et al. have demonstrated a novel three-angle deposition Manhattan style jun
ction fabrication process\, where the third angle deposition has the ion mi
ll step and creates a “patch” between the junction and shunting capacitor.
We discuss the fabrication and implementation of these in-situ patches with
our Ta transmon qubits. We then compare the measured coherence times of th
e qubits\, at a nominal temperature of 20 mK\, with and without these in-si
tu patches.
References:
[1] A. Dunsworth\, et al.\, Ap
pl. Phys. Lett. 111\, 022601 (2017).
[2] A. Osman\, et al.\, Appl. Phys.
Lett. 118\, 064002 (2021).
Advisor: Ben Palmer
LAST-MODIFIED:20250505T122036Z
LOCATION:1201 John S. Toll Bldg.
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Justin Mykel Peterkin
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20171120T160000
DTEND;TZID=America/New_York:20171120T170000
DTSTAMP:20260416T023943Z
UID:nfug9eack96h7gj383qiffh4ig@google.com
RECURRENCE-ID;TZID=America/New_York:20171120T160000
CREATED:20170417T185647Z
LAST-MODIFIED:20180117T182728Z
LOCATION:Room 1201 John S Toll Physics Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:THANKS GIVING BREAK -- NO STUDENT SEMINAR
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20201012T200000Z
DTEND:20201012T213000Z
DTSTAMP:20260416T023943Z
UID:24t7po7bng96poh53suc178rft@google.com
CREATED:20200909T180323Z
DESCRIPTION:Speaker: Shukai Ma\, UMD
Title: Reservoir Computing
in Chaotic Wave-based Systems
Abstract: \;
The ex
ecution of machine learning (ML) software largely depends on the computing
`substrate'\, which is often not optimized for running ML tasks. The invent
ion of ML-tailored hardware may greatly improve the computing speed and pow
er efficiency. Photonic devices are well-suited for ML due to the paralleli
sm of light. Reservoir computing (RC) is essentially a one-layer neural net
work (NN) with nonlinear connections\, but radically simpler than NN since
only the coupling between the reservoir nodes and outputs is trained. \
;
Here we utilize the complicated wave dynamics inside a cha
otic-shaped electromagnetic cavity containing nonlinear elements to emulate
the complex dynamics of an RC. Due to the short-wavelength property of the
waves\, their equivalent ray-propagation is chaotic. We propose unique tec
hniques to create virtual RC nodes by both frequency stirring and spatial p
erturbation. The computational power of the wave chaotic RC is experimental
ly demonstrated with the so-called observer task. Different tasks are execu
ted with a single RC physical device by simply switching output couplers. S
ince such systems are widely encountered in multiple settings (electromagne
tics\, quantum mechanics\, acoustics\, etc.)\, the work is of interest to m
any researchers in the physics and engineering communities.
This work is supported by ONR Grants No. N000141512134\, No. N000141912
481\, and AFOSR COE Grant FA9550-15-10171.
Advisor: Anlage Gr
oup
Zoom Link&nbs
p\; &\; \; \;Log In Information
Meeting ID: 911 980
3 7643 \;
Password:558484
LAST-MODIFIED:20201014T144328Z
LOCATION:Zoom
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Shukai Ma\, UMD
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20260413T200000Z
DTEND:20260413T210000Z
DTSTAMP:20260416T023943Z
UID:0h2d5n8o0djg1plkohrdmlocjf@google.com
CREATED:20260121T191426Z
DESCRIPTION:Title: Josephson Current through Topological Trilayer
YB6/SmB6/YB6 Junctions
Abstract: Samarium hexaboride (SmB6) is a to
pological Kondo insulator (TKI) characterized by robust topological surface
states and true bulk insulation. Previously\, we had observed perfect Andr
eev reflection in epitaxial heterostructures consisting of s-wave supercond
uctor YB6 and TKI SmB6 as a signature of topologicall
y protected superconducting Klein tunneling [1]. Recently\, we have succee
ded in fabricating topological Josephson junctions based on YB6/
SmB6/YB6 trilayers grown epitaxially on 3” Si wafers
by in-situ co-sputtering and patterned into vertical junction arrays using
standard photolithography. The junctions measured at temperatures down to 0
.8 K display resistively-shunted junction characteristics and well-behave
d Fraunhofer diffraction patterns. Clear Shapiro steps are observed upon mi
crowave irradiation. We are studying the details of the current distributio
n in the junctions of different SmB6 thicknesses through analysi
s of the Fraunhofer patterns at various temperatures. The ratio between the
critical current at zero magnetic field and that at the first side lobe is
indicative of an unconventional supercurrent density distribution\, while
the Josephson penetration depth places the devices in the small junction li
mit. The critical current ratio increases as the SmB6 layer thic
kness is increased through (double) the approximate thickness of the surfac
e state layer of SmB6\, indicating the suppression of tunneling
current as the bulk insulation becomes more pronounced. This work is funded
by AFOSR FA9550-14-10332.
[1] S. Lee et al. Nature 570\,
344–348 (2019).
LAST-MODIFIED:20260413T145320Z
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY: PHYS838C Seminar: Sungha Baek
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240212T160000
DTEND;TZID=America/New_York:20240212T170000
DTSTAMP:20260416T023943Z
UID:0a2690n68q78l6vnuatbc29u6s@google.com
RECURRENCE-ID;TZID=America/New_York:20240212T160000
CREATED:20240123T155408Z
LAST-MODIFIED:20240212T193613Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C -- NO SEMINAR
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20171106T160000
DTEND;TZID=America/New_York:20171106T170000
DTSTAMP:20260416T023943Z
UID:nfug9eack96h7gj383qiffh4ig@google.com
RECURRENCE-ID;TZID=America/New_York:20171106T160000
CREATED:20170417T185647Z
DESCRIPTION:SPEAKER: Guchhait Samaresh (Osborn)\n\nTIITLE: Broadband Two-L
evel System Defects Inversion Measured Through Dressed Resonator Frequency
and Dielectric Loss\n\nABSTRACT: Two-level system (TLS) defects are known t
o cause performance limiting decoherence in qubits and noise in astronomy p
hoton detectors. We have achieved a broadband TLS inversion in the GHz regi
me\, as monitored by a resonator. The TLS inversion is caused and controlle
d by application of a strong pump field and a swept electric field bias. Th
e resonator monitors the broadband TLS inversion through changes in its die
lectric permittivity and internal loss. For lowest bias rates\, TLSs are in
verted only close to pump energy due to relaxation processes and in this re
gime the frequency and loss are unchanged. With increasing bias rates\, a l
arger fraction of TLSs are inverted and distributed in energy below the res
onance frequency before relaxation. This causes the larger permittivity cha
nges\, up to a maximum value. For even larger bias rates\, a smaller fracti
on of TLSs are inverted initially due to large Landau-Zener tunneling ampli
tude and hence the shift in frequency and loss lowers from their respective
maximum values. Numerical simulations of permittivity change agree with ex
perimental results\, and give strong evidence for broadband TLS inversion.\
n\n===========================================\nSPEAKER: Seokjin Bae (Anla
ge)\n\nTITLE: Gap Spectroscopy for Unconventional Superconductors through t
he Anisotropic Nonlinear Meissner Effect\n\nABSTRACT: We present a new mea
surement method which can be used to image gap nodal structure of supercond
uctors whose pairing symmetry is unknown. This method utilizes photorespons
e from a microwave resonance of the superconducting sample perturbed by a s
canned laser spot. The anisotropy of this photoresponse is directly relate
d to that of gap function via the non-linear Meissner coefficient\, so the
gap nodal structures can be inferred from the photoresponse image. The sign
ificant advantage of the presented method over previous spiral or lumped ci
rcuit resonator methods is that it does not require a complicated lithograp
hic patterning process which often degrades superconductivity or introduces
defect-dominant photoresponse and hence limits one from testing various ki
nds of materials. The preliminary result obtained from unpatterned YBCO thi
n film which is one of the representative unconventional superconductor wil
l be shown and discussed.
LAST-MODIFIED:20180117T182728Z
LOCATION:Room 1201 John S Toll Physics Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20201102T210000Z
DTEND:20201102T223000Z
DTSTAMP:20260416T023943Z
UID:1bj95hvlql4aa8maable59hdut@google.com
CREATED:20200909T181249Z
DESCRIPTION:Speaker: \;Dr. Amalia Panella\, \;Gordon &\; Bet
ty Moore Foundation \; \;
Title: Career Speaker Series
Dr
. Panella will discuss her unexpected direction from grad school and postdo
c training to working as a foundation program manager. \; \;
The Career Speaker Series is meant to give advice to junior scientist on w
hat their choices are\, how life works after grad school\, what scientific
careers are out there.
Zoom Link \; &\; \; \;Log In Information
Meeting ID: 911 9803 7643 \;
Password:558484 \;
LAST-MODIFIED:20201106T173004Z
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar CAREER Speaker: Amalia Panella\, Gordon & Betty Mo
ore Foundation
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20251020T200000Z
DTEND:20251020T210000Z
DTSTAMP:20260416T023943Z
UID:08epcnahlk8gk695bnh6ot5egm@google.com
CREATED:20250825T190848Z
DESCRIPTION:\nPoint contact spectroscopy study of UTe$_2$ junctions\n\n\nSu
perconducting UTe2 has attracted wide interest for its unique characteristi
cs such as its reentrant superconductivity and proposed spin triplet superc
onductivity. However\, identifying an exact order parameter has proved quit
e difficult\, with various NMR\, ultrasound\, stress and other experiments
yielding at least 8 proposed representations. Here\, we make hard point con
tact junctions between UTe2 crystals and Pt/Ir tips to investigate the nonl
inear current-voltage behavior through the junctions. We present point cont
act junctions formed with varying barrier strengths and with multiple growt
h methods. The results of these differential conductance spectra at various
temperatures and fields\, once compared to BTK theory\, can provide insigh
t into the superconducting order parameter of UTe2.\n\nAdvisor: Paglione
LAST-MODIFIED:20251020T155602Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Lillian Jirousek
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170424T160000
DTEND;TZID=America/New_York:20170424T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170424T160000
CREATED:20170131T205940Z
DESCRIPTION:SPEAKER: Yangang Liang\nAdvisor: I. Takeuchi\n\nTITLE: W-dope
d VO2 thin films prepared by a combinatorial method for Li-ion battery appl
ications\n\nABSTRACT: Vanadium dioxide (VO2) has been extensively studied
due to its fully reversible first-order metal-insulator transition (MIT) as
sociated with a structural phase transition at about 68 °C. For potential w
ider applications in rechargeable lithium batteries\, we systematically stu
died the structural phase transition and the electronic properties of compo
sition spread V1-xWxO2 (0 ≤ x ≤ 0.037) thin films fabricated on silicon (00
1) and c-cut sapphire substrates through combinatorial pulsed laser deposit
ion of a VO2 target and a WO2 target. Electrical transport results show tha
t both the phase transition temperature and the width of the hysteresis loo
p decrease with the increasing of the concentration of tungsten. Especially
\, epitaxial V1-xWxO2 films fabricated on c-cut sapphire substrates show na
rrower hysteresis loop compared to textured V1-xWxO2 films fabricated on Si
(100) substrates. In addition\, we also studied the effects of substrate a
nd temperature on the crystal structures of V1-xWxO2. Moreover\, their pot
ential use as cathodes materials for rechargeable lithium batteries is inve
stigated.\n\n=================================================\n\nSPEAKER:
Pampa Sarkar\nAdvisor: R. Greene\n\nTITLE: Nernst effect in electron doped
cuprate superconductor La2-xCexCuO4\n\nABSTRACT: For nearly three decades\
, high TC cuprate superconductors have gained much scientific attention to
understand the pairing mechanism of superconductivity. We will discuss abou
t the Nernst signal measurements of epitaxial thin film of La2-xCexCuO4 fro
m underdoped (x = 0.08) to overdoped (x = 0.16) samples for a wide range of
temperature above TC. These measurements will be related to our present un
derstanding of the normal state and superconductivity in the cuprates. \n\n
LAST-MODIFIED:20170422T012624Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C Student Seminar
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20160229T160000
DTEND;TZID=America/New_York:20160229T170000
DTSTAMP:20260416T023943Z
UID:rmqmo3ba2jv9dsl4nuh0mig1ps@google.com
RECURRENCE-ID;TZID=America/New_York:20160229T160000
CREATED:20160204T164434Z
DESCRIPTION:SPEAKER: Kamala Bharathi (Takeuchi)\n\nTITLE: All Solid Thin
Film Batteries\n\nABSTRACT: Li ion batteries (LIB) are extensively used in
wide range of electrical and electronic devices such as laptops\, desktop
computers and mobile phones to most of the electrical vehicles. All solid b
atteries composed of cathode\, anode and electrolyte in solid form has seve
ral advantages such as improved safety\, absence of leakage related issues\
, high energy and power density compared to the conventional Li ion batteri
es having liquid electrolytes. In the present case\, feasibility of making
epitaxial cathode material thin films (Ex: LiCoO2\, Li2MnO3 etc…) of differ
ent orientations and utilization of the SrRuO3 layer as a bottom electrode
for measuring electrochemical properties of cathode films will be presented
. In addition to that\, Growth and evaluation of dielectric properties of L
i ionic conducting (Ex: LiLaTiO3) thin films on STO (100) and (111) substra
tes at different oxygen partial pressures will be demonstrated. Growth and
characterization of anode materials for the thin film based all solid batte
ries started with Li based oxide materials such as Li4Ti5O12 and LiTi2O4 wi
ll presented. Possibilities of fabrication of complete all solid thin film
battery device will be discussed at the end. \n----------------------------
---------------------------------------------------------------\nSPEAKER:
Luke Robertson (Kane)\n\nTITLE: Gallium Quantum Point Contacts on a 6-fol
d Degenerate Hydrogen-terminated Si(111) Surface\n\nABSTRACT: Hydrogen-ter
minated Si(111) surfaces preserve the 6-fold valley degeneracy and anisotro
pic electron mass predicted in bulk Si\, providing a unique environment for
2-D electron systems (2DESs). Our group has demonstrated high mobility as
well as the fractional quantum Hall effect for electrons confined on the Si
(111) surfaces\, establishing evidence that they are ideal platforms for 2D
ESs and lower dimensional systems. Recently\, we have succeeded in fabricat
ing high mobility ambipolar devices and have found that heavily p-doped reg
ions can be used as lateral depletion gates for confinement of 2DESs induce
d by a top gate [1]. Here\, we describe our efforts to extend this technolo
gy to the nanoscale and in particular towards the fabrication of quantum po
int contacts (QPCs). QPCs realized in materials with anisotropic electron m
ass may exhibit valley filter phenomena [2] leading to extreme sensitivity
to single donor occupancy\, and thus are of interest to measurement schemes
for donor-based quantum information processing. Preliminary measurements a
nd fabrication techniques will be discussed.\n\n[1] B. Hu\, et al\, arXiv\
, 1509.03849 (2015)\n[2] Gunawan et al\, Phys. Rev. B\, 74\, 155436 (2006
)\n------------------------------------------------------------------------
-----------------------
LAST-MODIFIED:20160418T191746Z
LOCATION:Room 1201 John S Toll Bldg
SEQUENCE:1
STATUS:CONFIRMED
SUMMARY:PHYS838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;VALUE=DATE:20251124
DTEND;VALUE=DATE:20251125
DTSTAMP:20260416T023943Z
UID:5flkmqqcgmke8clfd7i5jbhhfd@google.com
CREATED:20250825T191454Z
LAST-MODIFIED:20250825T191454Z
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Thanksgiving Week Break
TRANSP:TRANSPARENT
END:VEVENT
BEGIN:VEVENT
DTSTART:20230313T200000Z
DTEND:20230313T213000Z
DTSTAMP:20260416T023943Z
UID:2nd3crlpg69vnqjb16qbc1so83@google.com
CREATED:20230228T145542Z
DESCRIPTION:The Quantum Materials Center hosts a Career Seminar Serie
s that brings in prominent accomplished people (junior faculty\, na
tional lab scientist\, APS\, funding agency people etc.) to informally pres
ent their career history and aspects of their current job. Its meant to giv
e advice and a window to juniors on what their choices are\, how life works
after grad school\, what scientific careers are out there etc. All j
unior researchers (undergraduate\, graduate and postdocs) in our dept. are
welcome to participate in this virtual series. The next speaker and
connection info is listed below:
Alexander Shnirman\,
Karlsruher Institut für Technologie\, Germany
Magnetization Dynamics and Peierls Instability in Topological Josephson Str
uctures
We study a long topological Josephson junction with
a ferromagnetic stripe between the superconductors.
The low-energy theor
y exhibits a non-local in time and space interaction between chiral Majoran
a fermions\,
mediated by the magnonic excitations in the ferromagnet. Th
e spontaneous breaking of a Z2-symmetry at the
mean-field level leads to
a tilting of the magnetization and the opening of a fermionic gap (Majoran
a mass).
This is equivalent to the Peierls instability in the commensura
te Fröhlich model.
Within a Gaussian fluctuation analysis\, we identify
critical values for the temporal and spatial non-locality of the interacti
on\, beyond which the symmetry breaking is stable at zero temperature – des
pite the effective one-dimensionality of the model. We conclude that non-lo
cality\, i.e.\, the stiffness of the magnetization in space and time\, stab
ilizes the symmetry breaking. In the stabilized regime\, we expect the curr
ent-phase relation to exhibit an experimen- tally accessible discontinuous
jump. At nonzero temperatures\, as usual in the 1D Ising model\, the long-r
ange order is destroyed by solitonic excitations\, which in our case carry
each a Majorana zero mode.
Host: Victor Yakovenko
In-Person Location: Toll Physics Room # 1201
Time: 4pm -5:30pm
Also on Zoom: Meeting Link -
https://umd.zoom.us/j/97540478019
LAST-MODIFIED:20230308T134909Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar(CAREER TALK): Alexander Shnirman\, Karlsruher Inst
itut für Technologie\, Germany
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20200420T160000
DTEND;TZID=America/New_York:20200420T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20200406T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker 1: Haonan Xiong
Title: High coherence fluxonium
qubit and microwave-activated entangling gates
We report experiment
al progress on microwave-activated entangling gates with capacitively coupl
ed fluxonium qubits. When biased at the flux sweet-spot\, individual qubit
transition has long coherence (the best device has T2 >\; 400 us) [1]. A
control-Z gate can be implemented by sending a short 2π-pulse at the freque
ncy near the 1→2 transition of the target qubit [2]. The gate transition ha
s higher frequency and larger matrix element than the qubit transition\, re
sulting in fast gate and minimal spurious phase errors. Another microwave e
ntangling gate\, similar to the cross-resonance gate in transmon [3]\, can
be applied to the computational subspace. We discuss qubits' design and fab
rication\, initialization\, readout\, and benchmarking of the gates.
[1] Long B. Nguyen\, et. al.\, Phys. Rev. X (2019).
[2] Konstantin N.
Nesterov\, et. al.\, Phys. Rev. A 98\, 030301 (2018).
[3] Jerry M. Chow
\, et. al.\, Phys. Rev. Lett. 107\, 080502 (2011).
Speaker 2:Jingnan
Cai
Title: \;Chaos and Chimeras in Hysteretic RF SQUID Metamate
rialsRadio frequency Superconducting Quantum Interference Devic
e (rf SQUID) has been established as a viable building block for microwave
frequency metamaterials [1\,2]. The rf SQUID resonance is tunable under app
lied dc flux\, with upper-frequency range scaling as1+rf . Our previous des
ign restricted the parameter rf below unity to avoid hysteresis\, thus limi
ted the resonance range. We have built new arrays of RF SQUID meta-atoms in
the hysteretic regime to explore their interesting properties with the ult
imate goal of extending the resonance frequency tunability. Much theoretica
l work has predicted chaotic dynamics and chimera states in such systems. R
esults from microwave transmission measurements showing signs of these phen
omena will be reported. We will also discuss the future work of observing c
himera in laser scanning microscopy \; [3]. This work is supported by D
OE through grant # DESC0018788.
[1] Phys. Rev. X\, 3\, 0
41029 (2013) \; htt
ps://doi.org/10.1103/PhysRevX.3.041029
[2] Phys. Rev. X\
, 5\, 041045 (2015) htt
ps://doi.org/10.1103/PhysRevX.5.041045
[3] Appl. Phys. L
ett. 114\, 082601 (2019) https:
//doi.org/10.1063/1.5064658
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:7
STATUS:CONFIRMED
SUMMARY:Phys838C: No Class
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20170320T160000
DTEND;TZID=America/New_York:20170320T170000
DTSTAMP:20260416T023943Z
UID:jlnrisn1hdcot8ij4djmbcc1m0@google.com
RECURRENCE-ID;TZID=America/New_York:20170320T160000
CREATED:20170131T205940Z
LAST-MODIFIED:20170131T210422Z
LOCATION:Room 1201\, John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:NO Phys838C (Spring Break)
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191111T160000
DTEND;TZID=America/New_York:20191111T170000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
RECURRENCE-ID;TZID=America/New_York:20191111T160000
CREATED:20180117T182452Z
DESCRIPTION:Speaker:Hanho Lee\nTitle: Supercurrent transport in multi-termi
nal Josephson junctions\nAbstract:\nA non-dissipative current between two w
eakly coupled superconductors\, known as Josephson effect\, plays an import
ant role in basic physics and applications. We studied Josephson effect in
junctions of three and four superconductors\, called multi-terminal Josephs
on junctions (JJ). The devices are fabricated in a top-down fashion from ep
itaxially grown semiconductor/superconductor (InAs/Al) heterostructures. Su
percurrent transport is investigated based on critical current contour (CCC
) which provides a better way to characterize multi-terminal JJs. Those jun
ctions show multi-dimensional Fraunhofer interference pattern and gate depe
ndency. With a superconducting loop\, like a superconducting quantum interf
erence device (SQUID)\, periodic flux-dependent critical current contour is
observed in the devices.
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20260309T200000Z
DTEND:20260309T210000Z
DTSTAMP:20260416T023943Z
UID:343eg365k1vs86ecf9i6cnrtpv@google.com
CREATED:20260121T191203Z
DESCRIPTION:
Reversible Superconducting Digital Logic for Energy-Effic
ient ComputingThe rapid growth of computation has raise
d concerns about energy consumption\, motivating the
development of reve
rsible computing\, which operates differently from conventional irreversibl
e
logic. Reversible digital logic offers significant energy-efficiency a
dvantages and has potential
applications in astronomy detector readout a
nd quantum information science. Reversible Fluxon
Logic (RFL) is one of
the promising approaches\, using unpowered\, ballistic flux solitons
(fl
uxons) in long Josephson junctions (LJJs) to encode information. Logical ‘1
’ and ‘0’ are
represented by the polarity of fluxons pulses\, correspond
ing to clockwise and counterclockwise
circulating currents\, respectivel
y.
We first demonstrate a low-energy transmission line composed of d
iscrete LJJs\, consisting of 80
Josephson junctions with 7.5 μA critical
currents and connecting inductors. Measurements
confirm ballistic fluxo
n propagation\, with the transmission line operating in the continuous
r
egime and a fluxon rest energy of approximately 47 zJ. To characterize logi
c gate operations\,
we then implement a two-polarity detector (TPD) that
distinguishes fluxons by polarity\,
corresponding to the two-bit states
in our logic. We observe that one polarity requires a lower
bias curren
t due to a ground loop in the otherwise floating LJJ\, which can trap an ex
tra fluxon
along one path. Energy analysis of screening currents qualita
tively agrees with experimental data
and provides insight into flux beha
vior in ballistic reversible circuits. Building on these results\,
we de
sign a ballistic flip-flop (BFF) gate with a floating fluxons launcher that
avoids added
ground loop. Simulations demonstrate correct internal phas
es for gate initialization\, accurate
digital outputs for both fluxon po
larities\, and no asymmetry in the output bias. These studies
establish
our ballistic gate as a robust\, energy-efficient logic element\, compatibl
e with placement
near solid-state qubits at mK temperatures\, and demons
trate that ballistic logic is practical\,
providing a stable foundation
for scalable\, high-speed\, ultra-low-energy computing for next-
generat
ion computing systems.
Advisor: Kevin Osborn
LAST-MODIFIED:20260309T145034Z
LOCATION:1201 John S. Toll Bldg
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY: PHYS838C Seminar: Han Cai
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20230403T200000Z
DTEND:20230403T210000Z
DTSTAMP:20260416T023943Z
UID:5jfq12ss1lpco8me2fkrqg9gah@google.com
CREATED:20230221T144935Z
DESCRIPTION:
Nb-based superconductive electronics for future supercon
ducting digital computing
As we rapidly advance through t
he information age\, the amount of power consumed by computers\, data cente
rs\, and networks grows exponentially. This has inspired a race to develop
alternative low-power computational technologies. Superconducting computing
has been recognized as a promising solution for the post-Moore era\, which
shows ultrafast and low-power switching characteristics. Significant progr
ess has been made in developing superconducting systems based on low-TC sup
erconductors. Superconducting single flux quantum (SFQ) logic is one of the
superconducting systems\, which offers the potential for low-latency opera
tion with energy dissipation of the order of attojoules per gate. This pres
entation will discuss three critical components of SFQ circuits: LC resonat
or\, superconducting quantum interference device(SQUID)\, and single-flux-q
uantum (SFQ)/DC converter. The performance of superconducting devices is st
rongly dependent on the design and control of their inductance and capacita
nce. It is essential to carefully select appropriate values of these circui
t parameters to achieve high performance and energy efficiency in supercond
ucting circuits. To accomplish this\, we calculate self and mutual inductan
ce\, compare the performance with and without a ground plane\, and carefull
y control the measurement environment. These factors are critical to the su
ccessful development and optimization of superconducting devices.
Advisor: Kevin Osborn
In-Person Loca
tion: Toll Physics Room # 1201
Time: 4pm -5:00pm
Al
so on Zoom: Meeting Link - https://umd.zoom.us/j/9754047801
9
LAST-MODIFIED:20230329T195456Z
LOCATION:Toll Physics Room # 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:PHYS838C Seminar: Han Cai
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20180129T160000
DTEND;TZID=America/New_York:20180129T170000
RRULE:FREQ=WEEKLY;UNTIL=20180507T035959Z;BYDAY=MO
EXDATE;TZID=America/New_York:20180205T160000
EXDATE;TZID=America/New_York:20180312T160000
EXDATE;TZID=America/New_York:20180305T160000
EXDATE;TZID=America/New_York:20180319T160000
DTSTAMP:20260416T023943Z
UID:3kdb9qivnhpd74jjv5jupneh2u_R20180129T210000@google.com
CREATED:20180117T182452Z
DESCRIPTION:Speaker:
LAST-MODIFIED:20190109T201341Z
LOCATION:Toll bldg room 1201
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART:20240314T193000Z
DTEND:20240314T210000Z
DTSTAMP:20260416T023943Z
UID:7q03dn56ocmq1e7psojhqiume3@google.com
CREATED:20240308T001706Z
LAST-MODIFIED:20240308T001706Z
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:Faculty Candidate Meeting
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20180507T160000
DTEND;TZID=America/New_York:20180507T170000
RRULE:FREQ=WEEKLY;UNTIL=20200518T035959Z;BYDAY=MO
EXDATE;TZID=America/New_York:20180514T160000
EXDATE;TZID=America/New_York:20180521T160000
EXDATE;TZID=America/New_York:20180528T160000
EXDATE;TZID=America/New_York:20180604T160000
EXDATE;TZID=America/New_York:20180611T160000
EXDATE;TZID=America/New_York:20180618T160000
EXDATE;TZID=America/New_York:20180625T160000
EXDATE;TZID=America/New_York:20180702T160000
EXDATE;TZID=America/New_York:20180709T160000
EXDATE;TZID=America/New_York:20180716T160000
EXDATE;TZID=America/New_York:20180723T160000
EXDATE;TZID=America/New_York:20180730T160000
EXDATE;TZID=America/New_York:20180806T160000
EXDATE;TZID=America/New_York:20180813T160000
EXDATE;TZID=America/New_York:20180820T160000
EXDATE;TZID=America/New_York:20180827T160000
EXDATE;TZID=America/New_York:20180903T160000
EXDATE;TZID=America/New_York:20181210T160000
EXDATE;TZID=America/New_York:20181217T160000
EXDATE;TZID=America/New_York:20181224T160000
EXDATE;TZID=America/New_York:20181231T160000
EXDATE;TZID=America/New_York:20190107T160000
EXDATE;TZID=America/New_York:20190114T160000
EXDATE;TZID=America/New_York:20190121T160000
EXDATE;TZID=America/New_York:20190204T160000
EXDATE;TZID=America/New_York:20190304T160000
EXDATE;TZID=America/New_York:20190318T160000
EXDATE;TZID=America/New_York:20190408T160000
EXDATE;TZID=America/New_York:20190429T160000
EXDATE;TZID=America/New_York:20190506T160000
EXDATE;TZID=America/New_York:20190513T160000
EXDATE;TZID=America/New_York:20190520T160000
EXDATE;TZID=America/New_York:20190527T160000
EXDATE;TZID=America/New_York:20190603T160000
EXDATE;TZID=America/New_York:20190610T160000
EXDATE;TZID=America/New_York:20190617T160000
EXDATE;TZID=America/New_York:20190624T160000
EXDATE;TZID=America/New_York:20190701T160000
EXDATE;TZID=America/New_York:20190708T160000
EXDATE;TZID=America/New_York:20190715T160000
EXDATE;TZID=America/New_York:20190722T160000
EXDATE;TZID=America/New_York:20190729T160000
EXDATE;TZID=America/New_York:20190805T160000
EXDATE;TZID=America/New_York:20190812T160000
EXDATE;TZID=America/New_York:20190819T160000
EXDATE;TZID=America/New_York:20190826T160000
EXDATE;TZID=America/New_York:20190909T160000
EXDATE;TZID=America/New_York:20190916T160000
EXDATE;TZID=America/New_York:20190923T160000
EXDATE;TZID=America/New_York:20190930T160000
EXDATE;TZID=America/New_York:20191209T160000
EXDATE;TZID=America/New_York:20191216T160000
EXDATE;TZID=America/New_York:20191223T160000
EXDATE;TZID=America/New_York:20191230T160000
EXDATE;TZID=America/New_York:20200106T160000
EXDATE;TZID=America/New_York:20200113T160000
EXDATE;TZID=America/New_York:20200120T160000
EXDATE;TZID=America/New_York:20200316T160000
DTSTAMP:20260416T023943Z
UID:2pkcluicd7r49ju0l4hvd92t5o@google.com
CREATED:20180117T182452Z
DESCRIPTION:Speaker:
LAST-MODIFIED:20200515T011405Z
LOCATION:John S Toll Bldg\, Room 1201
SEQUENCE:6
STATUS:CONFIRMED
SUMMARY:Phys838C
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220207T160000
DTEND;TZID=America/New_York:20220207T173000
RRULE:FREQ=WEEKLY;WKST=SU;UNTIL=20220503T035959Z;BYDAY=MO
EXDATE;TZID=America/New_York:20220404T160000
EXDATE;TZID=America/New_York:20220502T160000
DTSTAMP:20260416T023943Z
UID:4vdu6nb1mlgqph41nks67m28hs_R20220207T210000@google.com
CREATED:20220121T185706Z
DESCRIPTION:Title: TBD
Abstract
: TBD
In-Person Location: Toll P
hysics Room # 1201
Time: 4pm -5:30pm
Zoom LInk: \;https://umd.zoom.us/j/97265681008