Practical quantum simulation of small-scale non-Hermitian dynamics

TL;DR

This paper introduces a quantum simulation protocol combining dilation and variational algorithms to effectively simulate small-scale non-Hermitian quantum dynamics within a closed system, overcoming experimental limitations.

Contribution

It presents a novel method to simulate non-Hermitian Hamiltonians using quantum circuits, enabling controlled studies of non-Hermitian phenomena.

Findings

Numerical simulations match theoretical predictions.

The protocol effectively simulates non-Hermitian dynamics.

Demonstrated on an Ising chain with nonlocal perturbations.

Abstract

Non-Hermitian quantum systems have recently attracted considerable attention due to their exotic properties. Though many experimental realizations of non-Hermitian systems have been reported, the non-Hermiticity usually resorts to the hard-to-control environments and cannot last for too long times. An alternative approach is to use quantum simulation with the closed system, whereas how to simulate non-Hermitian Hamiltonian dynamics remains a great challenge. To tackle this problem, we propose a protocol which combines a dilation method with the variational quantum algorithm. The dilation method is used to transform a non-Hermitian Hamiltonian into a Hermitian one through an exquisite quantum circuit, while the variational quantum algorithm is for efficiently approximating the complex entangled gates in this circuit. As a demonstration, we apply our protocol to simulate the dynamics of an Ising chain with nonlocal non-Hermitian perturbations, which is an important model to study quantum phase transition at nonzero temperatures. The numerical simulation results are highly consistent with the theoretical predictions, revealing the effectiveness of our protocol. The presented protocol paves the way for practically simulating small-scale non-Hermitian dynamics.