Topological photonics in non-Hermitian and scattering systems

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Abstract/Contents

Abstract
In photonics, topological effects can be used to design systems with robust and novel behavior. These topological effects are traditionally studied in closed systems without gain, described by Hermitian Hamiltonians. However, many systems in photonics do have gain or loss and can be described by non-Hermitian Hamiltonians. Systems with inputs and outputs are also widespread in photonics and are usually described by a scattering matrix. In this Thesis, we study topological features in non-Hermitian and scattering systems in photonics. First, we give a characterization of the space of all gapped non-Hermitian Hamiltonians using the mathematical framework of homotopy theory. We do this pedagogically in two-band systems, starting with the familiar Hermitian case before generalizing to the non-Hermitian setting, and then giving several physical interpretations of the results. Next, we study the topology of many-band non-Hermitian systems, and we see the importance of braid-group eigenvalue topology emerge. We provide a complete description of eigenvalue topology in gapped and gapless systems, again using the mathematics of homotopy theory. Finally, we move to scattering systems, where we study a topological feature in the spectrum of the scattering matrix known as a scattering threshold. Here, the scattering matrix has a square-root branch point, and we show that this singularity leads to a universal behavior in a wide variety of physical systems.

Description

Type of resource text
Form electronic resource; remote; computer; online resource
Extent 1 online resource.
Place California
Place [Stanford, California]
Publisher [Stanford University]
Copyright date 2022; ©2022
Publication date 2022; 2022
Issuance monographic
Language English

Creators/Contributors

Author Wojcik, Charles C
Degree supervisor Fan, Shanhui, 1972-
Thesis advisor Fan, Shanhui, 1972-
Thesis advisor Brongersma, Mark L
Thesis advisor Miller, D. A. B
Degree committee member Brongersma, Mark L
Degree committee member Miller, D. A. B
Associated with Stanford University, Department of Electrical Engineering

Subjects

Genre Theses
Genre Text

Bibliographic information

Statement of responsibility Charles C. Wojcik.
Note Submitted to the Department of Electrical Engineering.
Thesis Thesis Ph.D. Stanford University 2022.
Location https://purl.stanford.edu/mj287tr1114

Access conditions

Copyright
© 2022 by Charles C Wojcik

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