Chiral state conversion in a levitated micromechanical oscillator with in situ control of parameter loops

TL;DR

This paper demonstrates a controllable levitated microparticle system with two exceptional points, enabling the study of chiral state conversion through parameter loops and straight paths, expanding understanding of non-Hermitian physics.

Contribution

It introduces a novel, easy-to-control levitated microparticle platform with tunable parameter loops to explore chiral state conversion and exceptional point physics.

Findings

Chiral behavior observed along loops encircling EPs.

Chiral state conversion occurs even along straight paths away from EPs.

The system allows in situ control of loop structure, size, and location.

Abstract

Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian, which is degenerated at the exceptional points (EPs). Many new and unexpected features have been explored in the non-Hermitian systems with a great deal of recent interest. One of the most fascinating features is that, chiral state conversion appears when one EP is encircled dynamically. Here, we propose an easy-controllable levitated microparticle system that carries a pair of EPs and realize slow evolution of the Hamiltonian along loops in the parameter plane. Utilizing the controllable rotation angle, gain and loss coefficients, we can control the structure, size and location of the loops in situ. We demonstrate that, under the joint action of topological structure of energy surfaces and nonadiabatic transitions (NATs), the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP. This work broadens the range of parameter space for the chiral state conversion, and proposes a useful platform to explore the interesting properties of exceptional points physics.