Generation of Bell, W and GHZ states via exceptional points in non-Hermitian quantum spin systems

TL;DR

This paper demonstrates how exceptional points in non-Hermitian quantum spin systems can be used to generate highly entangled Bell, W, and GHZ states through dynamical evolution, combining analytical and numerical methods.

Contribution

It introduces a method to produce entangled states at exceptional points in non-Hermitian spin chains, expanding quantum state engineering techniques.

Findings

Exceptional points enable coalescing eigenstates close to entangled states.

High-fidelity generation of Bell, W, and GHZ states demonstrated.

Dynamical schemes effectively produce target states from proper initial conditions.

Abstract

We study quantum phase transitions in non-Hermitian XY and transverse-field Ising spin chains, in which the non-Hermiticity arises from the imaginary magnetic field. Analytical and numerical results show that at exceptional points, coalescing eigenstates in these models close to W, distant Bell and GHZ states, which can be steady states in dynamical preparation scheme proposed by T. D. Lee et. al. (Phys. Rev. Lett. 113, 250401 (2014)). Selecting proper initial states, numerical simulations demonstrate the time evolution process to the target states with high fidelity.