Wave transport in parity-time symmetric, time-varying, and quasi-periodic systems

The past several decades have witnessed a rapid growth of research interest in the fields of artificial materials and systems, in particular in the areas of parity-time symmetric systems, time-varying systems and quasi-periodic systems. These newly developed material platforms have been enabling many exotic wave-matter interaction phenomena unavailable in nature. In this context, I investigated a series of wave transport and scattering phenomena in parity-time symmetric, time-varying and quasi periodic systems in this dissertation. First, I proposed a sensing circuit based on sixth-order exceptional point (EP), which supports high sensitivity, resolution, and nondegraded thermal noise performance compared with conventional diabolic point (DP) sensing system. I also studied the influence of thermal noise in a general two-level sensing platform based on EP. Second, I demonstrated a robust microwave tunneling device operating in the extreme case in which the transmission channel is shorted through a small reactance. We observed full restoration of information and overall transparency to an external observer through use of a pair of parity-time-symmetric emitter and absorber. Third, I studied the effects of realistic switching parameters and synchronization in a series of nonreciprocal devices based on synchronized loss modulation. The research showed that the nonreciprocal response of these systems experiences a linear regression of insertion loss and isolation with respect to the timing error among switches. Remarkably, impedance matching, and nonreciprocal phase shifts are immune from synchronization issues, and reasonable levels of synchronization errors still guarantee low insertion loss and good isolation. Fourth, I studied wave scattering phenomena in static and dynamic quasi-periodic LC resonator array, which provides an easily accessible and reconfigurable platform to study fractal energy band and topological edge state. Overall, my explorations have been enabling a new degree of control of waves in circuits and metamaterials, pushing forward the opportunities for extreme wave-matter interactions using gain and time modulations.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Grantor

The University of Texas at Austin

Year dc:date.issued

2021

Author dc:creator

• Xiao, Zhicheng, 1987-

Advisor dc:contributor.advisor

• Alù, Andrea

Committee members dc:contributor.committeemember

• Kottos, Tsampikos
• Gharpurey, Ranjit
• Wasserman, Daniel
• Porter, Emily

• Non-Hermitian physics
• PT-symmetry
• Time modulation
• Quasi-periodicity
• Wave scattering

Language dc:language.iso

en

Identifier URI

http://dx.doi.org/10.26153/tsw/13733

OAI identifier oai:identifier

oai:repositories.lib.utexas.edu:2152/86782