Daria Kowsari

Abstract

The presence of the environment in real-world experiments which strive to harness quantum mechanical effects is inevitable. This results in dissipation, which is known to be the main source of errors that prevent us from building a practical quantum computer. Nevertheless, one can employ the environment as a resource, especially when there is a strong coupling between the system and its environment. In this regime, the dynamics of the system is governed by the generalized Nakajima-Zwanzig master equation incorporating all the memory effects induced by the environment. The existence of memory allows us to investigate intriguing phenomena, such as the revival of an entangled state. This acts as a measure to probe the characteristics of the environment. In this work, we study the evolution of an entangled state in this regime via a multi-qubit superconducting processor. In addition to the dissipation caused by the presence of the environment, the intrinsic material defects, e.g. the two-level system fluctuators, also contribute to the loss in superconducting circuits. To circumvent this issue, we explore a method to fabricate niobium superconducting circuits under high vacuum pressures to suppress the microwave loss caused by materials.

Committee Chair

Kater Murch

Committee Members

Erik Henriksen, Eli Levenson-Falk, Mikhail Tikhonov, David Wisbey

Degree

Doctor of Philosophy (PhD)

Author's Department

Physics

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

Spring 5-15-2023

Language

English (en)

Author's ORCID

http://orcid.org/0000-0002-5774-7848

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