Spring 2022

Motivated by recent experimental demonstrations of Floquet topological insulators, there have been several theoretical proposals for using structured light, either spatial or spectral, to create other properties such as flat band and vortex states. In particular, the generation of vortex states in a massive Dirac fermion insulator irradiated by light carrying nonzero orbital angular momentum (OAM) has been proposed recently. Here, we evaluate the orbital magnetization and optical conductivity as physical observables for such a system.

Dissertation Committee Chair: Professor Vladimir Manucharyan
Committee:
Professor Alicia Kollar
Professor Maissam Barkeshli
Professor Victor Yakovenko
Professor Andrew Childs (Dean’s Representative)

Abstract: Semiconductor moiré materials provide a physical realization of the Kane-Mele-Hubbard model for studies of the combined effects of non-trivial band topology and strong electronic correlations. In this talk, I will discuss the rich electronic phase diagram of the Kane-Mele-Hubbard model realized in AB-stacked MoTe2/WSe2 moiré bilayers.

Dissertation Committee Chair: Sankar Das Sarma
Committee:
Maissam Barkeshli
Alicia Kollar
Jay Sau
Andrew Childs
Additional Note: As this defense involves a public presentation, we request that attendees wear N95/KN95 masks as per current campus guidance for classes

Dissertation Committee Chair: Vladimir Manucharyan
Committee: 
Richard Greene
Steven Anlage
Jay Deep Sau
Ichiro Takeuchi

Dissertation Committee Chair: Mohammad Hafezi
Committee: 
Glenn Solomon
Sunil Mittal
You Zhou
Oded Rabin

Abstract: In general, quantum states are very sensitive to coupling to the environment. In many cases this interaction leads to a loss of coherence and a transformation of the quantum mechanical system to classical behavior. However, quantum states can also be stabilized if the environment and the coupling to it are appropriately engineered. This is the basic idea of the research results that I will present in this talk.

Abstract: Emergent two-dimensional (2D) atomic crystals [1,2] hold great promise for efficient control of magnetism, fundamentally owing to the 2D nature. However, thus far, there have been only proof-of-concept reports on electrical and optical control of 2D magnetism, and there appear to be some fundamental obstacles for the efficient control. In this talk, I will analyze the challenges and present our recent theoretical and experimental progress on efficient electrical and optical control of 2D magnetism [3-5].

Abstract: Strong exciton-photon interaction results in the formation of half-light half-matter quasiparticles called exciton-polaritons (EPs) that take on the properties of both its constituents. In this talk, I will first introduce polariton formation in 2D semiconductors  [1] followed by a discussion of Rydberg excitons [2] and dipolar excitons  [3] to realize highly nonlinear interactions to achieve polariton blockade.

Abstract: Neutron interferometry is practiced with de Broglie wavelengths of 0.1 nanometer over path lengths of 0.1 meter, typically in Mach-Zehnder configurations familiar to practitioners of atom and optical interferometry.