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:
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
Title: Physically Interpreting Negative and Imaginary Time Delays of Light in Scattering Systems
Abstract: The time a wave spends in a scattering system before exiting is called time delay, which becomes complex in subunitary scattering systems [1]. The real part of this quantity has been examined thoroughly, but little has been done in exploring the physical meaning behind the imaginary part. In 2016, authors in ref. [2]Theoretically demonstrated a connection between complex time delay and the propagation properties of a Gaussian pulse. Specifically, they found that the real part of complex time delay corresponds to a shift in transmission time of the pulse, and the imaginary part to be a shift in the center frequency of the pulse. We were able to experimentally test these predictions using a two port microwave ring graph setup and found excellent agreement between the predictions made by the authors in [2] and our experimental results.
For this talk I plan to first give some brief background on scattering systems and time delay. I then will be giving a brief overview of the past work on negative real time delay and how it is physically interpreted. Next I'll discuss imaginary time delay and the predictions made by Asano, et al. [2]. I will then present the experiment we designed to test these predictions, our results, and how we interpret them.
[1] Lei Chen, Steven M. Anlage, and Yan V. Fyodorov,“Generalization of Wigner Time Delay to Sub-Unitary Scattering Systems,” Phys. Rev. E 103, L050203 (2021).
[2] M. Asano, K. Y.Bliokh, Y. P. Bliokh, A. G. Kofman, R. Ikuta, T. Yamamoto, Y. S. Kivshar, L.Yang, N. Imoto, S. K. Ozdemir, and F. Nori, Anomalous time delays and quantum weak measurements in optical micro-resonators, Nat. Comm. 7, 13488 (2016).