Group Meetings Schedule 2021

Jan 20 (skipped due to Visa emergence), Haiping Hu, Wednesday 7:00 pm pitt time (Jan 21, 8:00 am Beijing time)

Jan 27, Zehan Li (rehearsal for defense), Wednesday 7:00 pm pitt time (Jan 28, 8:00 am Beijing time)

Feb 3, Haiping Hu, Exceptional Topological Insulator, Wednesday 7:00 pm pitt time (Feb 03, 8:00 am Beijing time)

Feb 17, Sayan Choudhury Prethermal Discrete Time Crystals Wednesday 7:00 pm pitt time (Feb 18, 8:00 am Beijing time)

March 10, Yang Ge (Postdoc Candidate) Wednesday 7:00 pm pitt time (March 11, 8:00 am Beijing time)

Title: Universal Landau-Zener regimes in dynamical topological phase transitions

Abstract: Topological quantum matters display fascinating response properties and robust edge states that put them at the center of continuous research. Generation, control and manipulation of topological matter proves to be a colorful theoretical playground and has become attainable in ultracold atom and condensed matter platforms in recent years. In this talk, I will discuss the dynamical preparation of the topological state of Floquet Chern insulators. I will show how a no-go theorem forbids transition between difference Chern insulator phases under unitary dynamics. In finite size systems, however, a topological phase transition can occur dynamically. Of the three regimes that the dynamics across these phase transitions falls into, we found that a universal Landau-Zener regime governs the behavior of dynamical topological phase transitions.

Daylight Saving Time Begins

March 17, Han Fu (Postdoc Candidate) 8:00 pm Pitt Time (March 18, 8:00 am Beijing time)

Title: Nonequilibrium dynamics in driven ultracold Bose systems and electron transport in disordered semiconductor systems

March 24, Zi-Yong Ge (Postdoc Candidate) 8:00 pm pitt time (March 25, 8:00 am Beijing time)

Title: Quantum simulation on superconducting circuits

Abstract: Superconducting circuits (SCCs) are believed to be one of the most competitive candidates for achieving the universal quantum computation and performing quantum simulation, due to the scalability, long coherent time, and high-precision control. In this talk, I will discuss my recent research progresses about quantum simulation via SCCs. Firstly, I will give a brief introduction of superconducting qubits. Then, I will discuss my two works about quantum simulation on SCCs in detail. One is the dynamics of Bose-Hubbard ladder model, where we find that there exists interesting pair localization. The other is how to simulate a Z2 lattice gauge theory on an 1D SCC. Finally, I will shortly introduce the ongoing quantum-simulation works I involved, and outline my future plans about the academic research

March 31, Grigory Bednik (Postdoc Candidate) 8:00 pm pitt time (April 1, 8:00 am Beijing time)

Title: Novel transport properties in topological semimetals at high magnetic fields

Abstract: Topological semimetals are characterized by unconventional electronic structure which leads to novel transport properties. In this talk I would like to discuss a few examples of such properties at high magnetic fields. In particular I discuss magnetoresistance of Weyl semimetals, its drag viscosity, second order response and thermopower. Also I consider nodal line semimetals and discuss their thermopower and neutron response. If time remains, I also would like to discuss my past work on surface states and antiferromagnetism in Dirac semimetals.

April 7, Bhaskar Mukherjee Wednesday 8:00 pm pitt time (April 8, 8:00 am Beijing time)

April 21, Zijian Wang Wednesday 8:00 pm Pitt time (April 22, 8:00 am Beijing time)

May 5, Haiping Hu Wednesday 8:00 pm Pitt time (May 6, 8:00 am Beijing time)

May 26, Sayan Choudhury Wednesday 8:00 pm Pitt time (May 27, 8:00 am Beijing time)

June 23, Sayan Choudhury Wednesday 8:00 pm Pitt time (June 24, 8:00 am Beijing time)

June 30, Sayan Choudhury Wednesday 8:00 pm Pitt time (July 1, 8:00 am Beijing time)

July 7, Yucheng Wang Wednesday 8:00 pm Pitt time (July 8, 8:00 am Beijing time)

Title: Mobility edges and critical phases in one-dimensional quasiperiodic systems.

July 28, Zijian Wang Wednesday 8:00 pm Pitt time (July 29, 8:00 am Beijing time)

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New Seminar Time

August 18, Kuldeep Suthar (Postdoctoral Candidate) Wednesday 8:00 am Pitt time (8:00 PM Beijing time)

Title: Quantum many-body states of dipolar bosons and thermal effects in square lattices

Abstract:

The long-range interaction of quantum many-body systems leads to exotic states of matter. In this talk, I will review our recent exploration of dipolar bosons in two-dimensional optical lattices. We shall first discuss the stability of supersolid phase in synthetic quantum matter and the role of quantum fluctuations in various phase transitions using cluster-size scaling. Furthermore, we will discuss the effects of thermal fluctuations at finite temperatures on the existence of supersolidity of lattice bosons. The variation in the tilt of dipolar bosons gives rise to phases with different diagonal orders. The ultracold dipolar gases provide a unique opportunity to characterize the role of density-induced correlated hopping. We use cluster Gutzwiller approach to examine the interference between single-particle and correlated tunnelings. I will show the emergence of staggered superfluidity at vanishing kinetic energies. Finally, we shall discuss the demixing properties with intra- and interspecies long-range interaction of the dipolar bosonic mixtures.

August 25, Haiping Hu Wednesday 8:00 am Pitt time (8:00 PM Beijing time)

September 8, Changyong Lei (PD Candidate) Wednesday 8:00 am Pitt time (8:00 PM Beijing time)

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New Seminar Time

September 15, Lu Yao Wednesday 8:00 PM Pitt time (Thursday, Sep 16 8:00 AM Beijing time)

Topic: A brief introduction to trapped ion systems

September 27- October 1: KITP Conference on "Non-Equilibrium Universality in Many-Body Physics"

Sayan will be visiting in-person

Talks will be available at : https://www.kitp.ucsb.edu/activities/universality-c21

October 6, Yi Peng, Wednesday 8:00 PM Pitt time (Thursday, October 7 8:00 AM Beijing time)

October 20, Sayan Choudhury, Wednesday 8:00 PM Pitt time (Thursday, October 21 8:00 AM Beijing time)

Topic: Classical prethermal discrete time crystals

October 27, Georg Engelhardt, Wednesday 8:00 PM Pitt time (Thursday, October 21 8:00 AM Beijing time)

Title:

Floquet response theory and spectroscopy: exotic stationary states, dark states, quantum light, and comparison to the standard nonlinear response theory

Abstract:

In the recent decades, the light-matter interaction could be pushed to the strong coupling regime in different experimental platforms, such as superconducting qubits, cold atoms in optical cavities, and molecules in polaritonic cavities. This opens up new chances for the quantum control, but imposes also theoretical challenges. Recently, Floquet response theory has been developed to describe quantum systems which are subject to a possible strong, but periodic driving field, and a weak, but arbitrary probe field.

In this talk, we explain how to treat spectroscopy of strongly-driven quantum system based on the input-output theory and the Floquet response theory, such that distinct optical effects can be described on equal footing. In this context, we address several important findings: (i) The investigation of stationary states of periodically-driven quantum systems shows that they can strongly deviate from the so-called Floquet-Gibbs ensembles and can exhibit exotic non-analytic behavior which is visible in the emission [1]; (ii) The study of dynamically-generalized symmetries demonstrate the appearance of dark-states and selection rules for inelastically scattered light [2]; (iii) The generation of squeezed and entangled light is possible by a device of sequentially-coupled strongly-driven quantum systems, which are described by the Floquet response theory; (iv) A comparison of Floquet response theory and the standard nonlinear response theory shows that both frameworks are not equivalent.

[1] G. Engelhardt, G. Platero, and J. Cao, Phys. Rev. Lett. 123, 120602 (2019) [2] G. Engelhardt, and J. Cao, Phys. Rev. Lett. 126, 090601 (2021)

November 3, Bhaskar Mukherjee, Wednesday 8:00 PM Pitt time (Thursday, Nov 4 8:00 AM Beijing time)

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Daylight Savings Ends

November 17, Yucheng Wang, Wednesday 7:00 PM Pitt time (Thursday, Nov 18 8:00 AM Beijing time)

December 1, Haiping Hu, Wednesday 7:00 PM Pitt time (Thursday, December 2 8:00 AM Beijing time)

December 22, Linhu Li, Wednesday 7:00 PM Pitt time (Thursday, December 23 8:00 AM Beijing time)

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Meetings reconvene on January 12 Pitt time (January 13 Beijing time)