Photonic quantum simulations of coupled $PT$-symmetric Hamiltonians

TL;DR

This paper demonstrates the use of a programmable photonic chip to simulate coupled $PT$-symmetric Hamiltonians, revealing complex quantum behaviors at exceptional points and showcasing the potential of quantum simulators for foundational studies.

Contribution

It introduces a novel photonic quantum simulation platform for coupled $PT$-symmetric Hamiltonians, enabling exploration of quantum dynamics across exceptional points.

Findings

Simulation of quantum dynamics across exceptional points

Observation of two- and three-particle interference effects

Detection of particle-trembling behavior due to time-reversed evolutions

Abstract

Parity-time ($PT$) symmetric Hamiltonians are generally non-Hermitian and give rise to exotic behaviour in quantum systems at exceptional points, where eigenvectors coalesce. The recent realisation of $PT$-symmetric Hamiltonians in quantum systems has ignited efforts to simulate and investigate many-particle quantum systems across exceptional points. Here we use a programmable integrated photonic chip to simulate a model comprised of twin pairs of $PT$-symmetric Hamiltonians, with each the time reverse of its twin. We simulate quantum dynamics across exceptional points including two- and three-particle interference, and a particle-trembling behaviour that arises due to interference between subsystems undergoing time-reversed evolutions. These results show how programmable quantum simulators can be used to investigate foundational questions in quantum mechanics.