Physics 838 Graduate Student Seminar

In 1990, a seminar was initiated for QMC (formerly CNAM/CSR) graduate students in order to present their research to the other students, postdocs, and faculty in the Center. In addition to fostering a rich, collaborative environment in which students learn about the breadth and scope of research being done in QMC, the idea of this series is to teach several crucial skills to our students:

1) How to present their research in a clear and time-efficient way to an audience that was not expert in their area of research;

2) How to best answer questions during their presentations;

3) How to ask good questions when in an audience (or interview), in particular about research beyond their own narrow PhD topic.

In this seminar, students submit formalized feedback to each weekly presenter, providing informative information about presentation style, research content and tips for improvement.

Best Speaker Awards

At the end of each term, a cash prize award is given for the best student and postdoc presentations based on class feedback scores. Previous winners are listed here:

2023 (fall) Jared Erb (student), Peter Czajka (postdoc)

2022 (fall) Sungha Baek (student), Keenan Avers (postdoc)

2020 (fall) Shukai Ma 

2019 (spring) Rui Zhang (student), Tarapada Sarkar (postdoc)

2018 (fall) Chris Eckberg (student), Jen-Hao Yeh (postdoc)

2015 Paul Syers, Jasper Drisko

2014 Sean Fackler, Paul Syers,

2013 Kevin Kirshenbaum, Kirsten Burson

2012 Baladitya Suri, Kristen Burson

2011 (fall) Sergii Pershoguba, Ted Thorbeck

2011 (spring) Anirban Gangopadhyay, Baladitya Suri

2010 (fall) Christian J. Long, Tomasz M. Kott

2010 (spring) Tomasz M. Kott, Kevin Kirshenbaum

2009 (fall) Arun Luykx, Jen-Hao Yeh

PHYS838C Seminar: Haonan Xiong, UMD

Calendar
Physics 838 Seminar
Date
03.08.2021 4:00 pm - 5:30 pm

Description

Speaker: Haonan Xiong
Title: Two-qubit gates on fluxonium
Abstract:
Switching the interaction between qubits on-demand and with minimal resources is essential for scalable quantum computing. In superconducting circuits, the weak anharmonicity of transmons creates many design challenges, leading to more complex circuits and pulse protocols, slower gates, and higher gate errors. Here we describe a minimalistic scheme to control interactions between strongly-anharmonic fluxonium qubits, connected by a permanent capacitive link. Specifically, we show that off-resonant driving of non-computational transitions in either qubit induces a clean ZZ-interaction due to ac-Stark shifts of the four computational levels. With proper frequency and amplitude, the drive can cancel the static ZZ-interaction. We also demonstrate controlled-Z gates and other controlled-phase gates between capacitively coupled fluxonium qubits. The gate is activated by using non-computational transitions 10-20 and 11-21. The measured gate error less than 0.01 is limited by decoherence, which will likely improve in the next generation devices. Architectural advantages of low-frequency fluxoniums include long qubit coherence time, weak hybridization in the computational subspace, suppressed residual ZZ-coupling rate, and absence of either excessive parameter matching or complex pulse shaping requirements. Our demonstration generally applies to strongly-anharmonic qubits, and it opens a new route for reducing errors and increasing circuit depth of quantum algorithms executed on fluxonium-based processors.

Advisor: Vladimir Manucharyan







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