Date of Award

Spring 1-1-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

Schoelkopf, Robert

Abstract

Modern quantum experiments allow the precise manipulation and measurement of many-body quantum states, pushing quantum mechanics from a testable theory to a utilizable technology. The central promise of these experiments is to process quantum information for exponential advantages in computing, sensing, and communication. An interesting way to achieve such a processor is to manipulate quantum information stored in the continuous-variable (bosonic) phase space of electromagnetic radiation. Since photons in free space do not interact, such an approach necessarily requires the introduction of nonlinearity through strong light-matter couplings. However, since all matter is lossy, this inevitably introduces a trade-off between the speed of control and the inherited decoherence of the ‘light.’

This thesis explores the control of microwave radiation trapped in superconducting oscillators through interactions with Josephson junction-based nonlinearities. I first demonstrate novel ways to exchange single photons between two detuned oscillators through carefully constructed driven nonlinearities, achieving orders of magnitude higher fidelity than previously possible. Using such protected driven interactions, I then implement a bosonic control architecture and that is protected from any nonlinearity when idle, and implements clean photon-exchanges when driven. Finally, I introduce ways to utilize such photon-exchanges to dynamically hybridize light and matter, in a way that regains universal control without reintroducing the inherited decoherence. Together, this thesis provides a promising path toward error-resilient bosonic quantum processors.

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