Theses and Dissertations

Date of Award

5-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics

First Advisor

Dr. Hamidreza Ramezani

Second Advisor

Dr. Ahmed Touhami

Third Advisor

Dr. Cem Yuce

Abstract

A closed system associated with Hermitian Hamiltonian allows real eigenvalues. However, the behavior and dynamics an open system (with gain and loss) will be addressed through the Non-Hermitian Hamiltonian. Though a non-Hermitian operator can allow only imaginary eigenvalues, if the Hamiltonian of a non-Hermitian operator obey the combined parity time (PT)-reversal symmetry it exhibits the real eigenvalues or energy spectrum. That is where the topology comes into account. If we add gain, loss or disorder in the system in such a way that the topology of the system does not change and keeping the topology robust under such disorder we can see many exotic phenomena in both optics and acoustic, like the phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices. Whereas a trivial topological insulator only allows topologically robust edge states, we investigate a one-dimensional tight binding lattice where topologically robust bulk state is observed, which canpave a way to direct transport of acoustic or optical signal through the bulk. In this thesis we will explore the behavior such a system as well as discuss our experimental findings to support our claims. We will also demonstrate how we built a tunable non-Hermitian acoustic filter by adjusting the non-Hermiticity in the system and show how experimental data verifies simulation. The detailed explanation of experimental setup, devices used, data acquisition, post processing will be presented in the last part of the thesis.

Comments

Copyright 2021 Jannatul Ferdous. All Rights Reserved.

https://go.openathens.net/redirector/utrgv.edu?url=https://www.proquest.com/dissertations-theses/topologically-robust-bulk-state-non-hermitian/docview/2572584482/se-2?accountid=7119

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