Spring 2022

Recently, there has been remarkable progress towards the development of large-scale quantum devices through advances in quantum science and technology. This progress opens new doors for proof-of-principle demonstrations of quantum simulations as well as practically useful applications, such as quantum-enhanced metrology and quantum networking.

Abstract: Dirac Spin Liquids (DSLs) are gapless symmetric states in 2+1 dimensions with no magnetic order. They are featureless, yet interesting because their low energy physics is believed to be described by QED-3, an effective field theory in terms of gapless Dirac fermions coupled to an emergent U(1) gauge field. They also serve as a parent state for seemingly unrelated magnetically ordered states, where the ordered states arise from condensation of ``monopole excitations” of the DSL. Can such a description have experimentally observable consequences?

Abstract: Fractons are a class of quasiparticles that cannot freely propagate through space. They were first introduced in a model of quantum (almost) self-correcting memory. Later it became clear that fractons, as well as, adjacent ideas such as tensor gauge theories and multipole or subsystem conservation laws provide a language to describe some known and some new phenomena. In this talk I will explain what fractons are, what kind of systems are known to support them and what kind of problems they will help to elucidate in the future.
Location: ATL 4402

Dissertation Committee Chair: Prof. Zohreh Davoudi
Committee: 
Prof. Ian Spielman
Prof. Jacob Taylor
Prof. Norbert Linke
Prof. Xiaodi Wu
Prof. Justyna Zwolak

Abstract: Magic-angle (θ=1.05∘) twisted bilayer graphene (MATBG) has shown two seemingly contradictory characters: the localization and quantum-dot-like behavior in STM experiments, and delocalization in transport experiments. We construct a model, which naturally captures the two aspects, from the Bistritzer-MacDonald (BM) model in a first principle spirit. A set of local flat-band orbitals (f) centered at the AA-stacking regions are responsible to the localization.

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.

Abstract:  We argue that all locality-preserving mappings between fermionic observables and Pauli matrices on a two-dimensional lattice can be generated from the exact bosonization (arXiv:1711.00515), whose gauge constraints project onto the subspace of the toric code with emergent fermions. Starting from the exact bosonization and applying Clifford finite-depth generalized local unitary (gLU) transformation, we can achieve all possible fermion-to-qubit mappings (up to the re-pairing of Majorana fermions).

Learning how to create, study, and manipulate highly entangled states of matter is key to understanding exotic phenomena in condensed matter and high energy physics, as well as to the development of useful quantum computers. In this talk, I will discuss recent experiments where we demonstrated the realization of a quantum spin liquid phase using Rydberg atoms on frustrated lattices and a new architecture based on the coherent transport of entangled atoms through a 2D array.

In the past decade a new technology domain of quantum sound has emerged. Unlike electrical and optical systems, which are governed by fundamental equations of electromagnetism, acoustical and vibrational phenomena are described by the equations of elastic waves in solid bodies. They are subject to different limitations and can reach different regimes of behavior. Sound is different.