Dynamics of a tight-binding ring threaded by time-periodic magnetic flux

TL;DR

This paper analytically explores how periodic magnetic fields influence quantum state dynamics in a tight-binding ring, demonstrating methods to coherently freeze states and optimize quantum state engineering.

Contribution

It introduces a method to coherently freeze quantum states in a tight-binding ring using periodic magnetic fields, with analysis of optimal parameters and fidelity dependence.

Findings

Quantum states can be coherently frozen using periodic magnetic fields.

Average fidelity depends on system parameters and quantum state features.

Threshold frequency varies with wave packet width for desired fidelities.

Abstract

We analytically study the effects of periodically alternating magnetic fields on the dynamics of a tight-binding ring. It is shown that an arbitrary quantum state can be frozen coherently at will by the very frequent square-wave field as well as the monochromatic-wave field when the corresponding optimal amplitudes are taken. Numerical simulations show that the average fidelity depends on not only the system parameters, but also the features of the quantum state. Moreover, taking the initial zero-momentum Gaussian wave packets as examples, we show the dependence of the threshold frequency on the width of the packet for the given average fidelities. These observations provide a means to perform the quantum state engineering.