Amplitude control of a quantum state in a non-Hermitian Rice-Mele model driven by an external field

TL;DR

This paper investigates how a non-Hermitian Rice-Mele model's quantum state amplitude can be controlled via an external field, revealing real spectra and complex Berry phases that enable amplitude modulation.

Contribution

It provides exact analytical results on the real spectrum and Berry phase behavior in a non-Hermitian Rice-Mele model driven by an external field, demonstrating amplitude control through quasi-adiabatic processes.

Findings

The model maintains a real spectrum for any external field value.

The Berry phase remains a complex constant across initial states in a sub-band.

Amplitude control is achievable via a short-time quasi-adiabatic process.

Abstract

In the Hermitian regime, a Berry phase is always the real number. It may be imaginary for a non-Hermitian system, which leads to amplitude amplification or attenuation of an evolved quantum state. We study the dynamics of the non-Hermitian Rice-Mele model driven by a time-dependent external field. The exact results show that it can have full real spectrum for any value of the field. Several rigorous results are presented for the Berry phase with respect to the varying field. We show that the Berry phase is the same complex constant for any initial state in a single sub-band. Numerical simulation indicates that the amplitude control of a state can be accomplished by a quasi-adiabatic process within a short time.