Spring 2024

Abstract: The unification of quantum mechanics and gravity is a major outstanding goal. One modern approach to understanding this unification goes by the name ``holography’’, in which gravity can be understood as an emergent description of some more fundamental, purely quantum mechanical system. In this talk I will describe some recent results in holography that elucidate how this emergence works. A starring role will be played by one-shot quantum information theory.

Abstract: Circuit quantum electrodynamics (circuit QED) has become one of the main platforms for quantum simulation and computation. One of its notable advantages is its ability to facilitate the study of new regimes of light-matter interactions. This is achieved due to the native strong coupling between superconducting qubits and microwave resonators, and the ability to lithographically define a large variety of resonant microwave structures, for example, photonic crystals.

Dissertation Committee Chair: Prof. Steve Rolston

Committee: 

Prof. Gretchen Campbell

Prof. Nathan Schine

Prof. Ron Walsworth

Prof. Ki-yong Kim

Abstract: The past fifty years of scientific and technological progress have clearly highlighted information as a physical resource - one that can be traded for heat, work, and other energetic resources. With the ongoing new wave of quantum-based technologies, understanding the microscopic and emergent dynamics of quantum information in many-body quantum systems has thus become a priority.

Abstract: Nagaoka ferromagnetism (NF) is a long-predicted example of itinerant ferromagnetism in the Hubbard model and has been studied theoretically for many years. NF occurs when there is one hole in a half-filled band and a large onsite Coulomb repulsion, which does not arise naturally in materials. Quantum dots systems like dopant arrays in Si, can be fabricated with atomically precise complex geometries to create highly controllable systems. This makes them good candidates to study itinerant ferromagnetism in different array geometries.

Dissertation Committee Chair: Mohammad Hafezi and Kartik Srinivasan

Committee: 

Yanne Chemo

Efrain Rodriguez

Edo Waks

Xiyuan Lu

Abstract: Theories whose fluctuating degrees of freedom live on extended loops as opposed to points, are abundant in nature. One example is the action obtained upon eliminating the redundant gauge fields in a gauge theory. Formulating a Renormalization Group (RG) procedure for such a theory is an open problem. In this work, we outline a procedure that in principle computes the outcome of coarse-graining and rescaling of such a theory. We make estimates that lead to qualitative agreement with known results of phase transitions in gauge theories and the XY-model.

Dissertation Committee Chair: Professor Alicia Kollár

Committee: 

Professor Norbert Linke, Advisor and Co-Chair

Professor Zohreh Davoudi

Professor Ian Spielman

Professor Xiaodi Wu

Dissertation Committee Chair: Professor Alicia Kollár

Committee:

Professor Mohammad Hafezi (Dean’s Representative)

Professor Steven Rolston

Professor Trey Porto

Professor Sarah Eno

Abstract: Noise on quantum devices is much more complex than it is commonly given credit. Far from usual models of decoherence, nearly all quantum devices are plagued both by a continuum of environments and temporal instabilities. These induce noisy quantum and classical correlations at the level of the circuit. The relevant spatiotemporal effects are difficult enough to understand, let alone combat. There is presently a lack of either scalable or complete methods to address the phenomena responsible for scrambling and loss of quantum information.