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:

2025 (fall) Jared Dans (student)

2025 (spring)  Jarryd Horn (student)

2024 (fall) Jared Erb (student)

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: Jason Dong

Calendar
Physics 838 Seminar
Date
03.02.2026 4:00 pm - 5:00 pm
Location
John S. Toll Room 1201

Description

Title: Molecular beam epitaxy of Germanium quantum wells Josephson Junctions with epitaxial aluminum

Abstract: High mobility strained Ge quantum wells (QWs) have been of interest as a material host for hole spin qubits and superconducting-semiconducting Josephson junctions (JJs). To date, these Ge QWs JJs have been fabricated using chemical vapor deposition(CVD) grown material with ex-situ superconducting contacts. Epitaxial superconducting contacts are often desired in superconductor/semiconductor JJs because of their high transparency and consistency.

In this work, we investigate the growth of Ge QWs on float zone silicon substrates with MBE. Ge QWs with varying top spacer thickness were grown. The growth conditions to optimize the mobility of the MBE-grown Ge QWs is investigated. Low temperature mobilities exceeding 120,000 cm2/Vsare obtained in Ge QWs with a 22-nm top spacer, representing the highest mobility for MBE-grown Ge QWs, by optimizing the layer thickness and the growth temperature. Modeling the density dependence of mobility of samples indicates that surface scattering is the limiting scattering mechanism in shallow QWs, while interface roughness scattering is the limiting mechanism in deeper quantum wells. Further improvements to the mobility will be discussed. In samples with the top spacer thickness varying from 5-nm to 22-nm and epitaxial Al, the trade off of top spacer thickness on mobility, mean free path, and transparency are investigated. These findings demonstrate MBE-grown Ge QWs asan emerging platform for quantum computing.




Advisor: Chris Richardson