Spring 2024

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.

Abstract: In gradient descent dynamics of neural networks, the top eigenvalue of the Hessian of the loss (sharpness) displays a variety of robust phenomena throughout training. This includes early time regimes where the sharpness may decrease during early periods of training (sharpness reduction), and later time behavior such as progressive sharpening and edge of stability. We demonstrate that a simple $2$-layer linear network (UV model) trained on a single training example exhibits all of the essential sharpness phenomenology observed in real-world scenarios.

Committee: Steven Rolston (chair)

Ian Spielman (advisor)

Mohammad Hafezi (dean's rep)

William Phillips

Trey Porto

Abstract: In order to simulate interacting fermionic systems on quantum computers, the first step is to encode the physical Hamiltonian into qubit operators. Existing encoding procedures such as the Jordan-Wigner transformation and Bravyi-Kitaev transformation are not resource efficient because they encode each second-quantized fermionic operator into a Pauli string without incorporating the structure of the Hamiltonian in question.

Abstract: Light emitters within two-dimensional arrays have been demonstrated to exhibit various cooperative effects, including super- and sub-radiance, collective line-shift and linewidth, and topological features such as Chern bands and edge states. Motivated by these intriguing properties, the realization of emitter arrays has been attempted in cold atom experiments, which nevertheless cannot access the deep subwavelength regime.

Dissertation Committee Chair: Daniel Lathrop

Committee: 

Ian Spielman

Nathan Schine

Thomas Antonsen

Johan Larsson (Dean’s Rep)