R. G. Herb Condensed Matter Seminars |
||
| << Fall 2021 | Spring 2022 | Summer 2022 >> |
| Subscribe to receive email announcements of events | ||
Events During the Week of February 6th through February 13th, 2022
Monday, February 7th, 2022
- No events scheduled
Tuesday, February 8th, 2022
- Novel optical probes in the study of condensed matter systems
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Ilya Esterlis, Harvard University
- Abstract: A great deal of our understanding of condensed matter comes from observing how materials interact with light. In recent years, the development of novel optical probes has opened yet a new route by which to investigate condensed matter systems, allowing to both interrogate interesting materials that are challenging to study by conventional means and also yielding information in complementary parameter regimes. I will focus on two such probes: exciton spectroscopy in 2D semiconductors and sensing with nitrogen-vacancy (NV) centers in diamond. As a concrete demonstration, I will describe (1) how these probes have been utilized to establish the existence of Wigner crystal phases — the solid phase of the interacting electron gas — in 2D transition-metal dichalcogenide (TMD) systems and (2) how they may further elucidate properties of the electron solid and also shed light on the nature of the corresponding liquid-solid transition, where effects such as frustrated magnetism and impurity interactions are expected to result in exotic and fascinating physics. Finally, I will provide some outlook on the promise of these techniques to investigate more general classes of interesting condensed matter systems.
- Host: Robert McDermott
Wednesday, February 9th, 2022
- No events scheduled
Thursday, February 10th, 2022
- NISQ: Error Correction, Mitigation, and Noise Simulation
- Time: 10:00 am
- Place: virtual:
- Speaker: Bei Zeng, The Hong Kong University of Science and Technology
- Abstract: Error-correcting codes were invented to correct errors on noisy communication channels. Quantum error correction (QEC), however, may have a wider range of uses, including information transmission, quantum simulation/computation, and fault-tolerance. These invite us to rethink QEC, in particular, about the role that quantum physics plays in terms of encoding and decoding. The fact that many quantum algorithms, especially near-term hybrid quantum-classical algorithms, only use limited types of local measurements on quantum states, leads to various new techniques called Quantum Error Mitigation (QEM). This work addresses the differences and connections between QEC and QEM, by examining different application scenarios. We demonstrate that QEM protocols, which aim to recover the output density matrix, from a quantum circuit do not always preserve important quantum resources, such as entanglement with another party. We then discuss the implications of noise invertibility on the task of error mitigation, and give an explicit construction called quasi-inverse for non-invertible noise, which is trace-preserving while the Moore-Penrose pseudoinverse may not be. We also study the consequences of erroneously characterizing the noise channels, and derive conditions when a QEM protocol can reduce the noise. virtual:
- Host: Mark Saffman
Friday, February 11th, 2022
- No events scheduled