Entanglement Dynamics in Anti-$\mathcal{PT}$-Symmetric Systems

TL;DR

This paper explores the evolution of entanglement in anti-$\mathcal{PT}$-symmetric quantum systems, revealing unique oscillation patterns, entanglement sudden vanishing and revival, and experimental validation with optical setups.

Contribution

It provides the first theoretical and experimental analysis of entanglement dynamics in $\mathcal{APT}$-symmetric systems, uncovering novel phenomena and behaviors.

Findings

Periodic entanglement oscillations in unbroken regime

Entanglement sudden vanishing and revival near exceptional points

Rapid decay and delayed death of entanglement in broken regime

Abstract

In the past years, many efforts have been made to study various noteworthy phenomena in both parity-time ($\mathcal{PT}$) and anti-parity-time ($\mathcal{APT}$) symmetric systems. However, entanglement dynamics in $\mathcal{APT}$-symmetric systems has not previously been investigated in both theory and experiments. Here, we investigate the entanglement evolution of two qubits in an $\mathcal{APT}$-symmetric system. In the $\mathcal{APT}$-symmetric unbroken regime, our theoretical simulations demonstrate the periodic oscillations of entanglement when each qubit evolves identically, while the nonperiodic oscillations of entanglement when each qubit evolves differently. In particular, when each qubit evolves near the exceptional point in the $\mathcal{APT}$-symmetric unbroken regime, there exist entanglement sudden vanishing and revival. Moreover, our simulations demonstrate rapid decay and delayed death of entanglement provided one qubit evolves in the $\mathcal{APT}$-symmetric broken regime. In this work, we also perform an experiment with a linear optical setup. The experimental results agree well with our theoretical simulation results. Our findings reveal novel phenomena of entanglement evolution in the $\mathcal{APT}$-symmetric system and opens a new direction for future studies on the dynamics of quantum entanglement in multiqubit $\mathcal{APT}$-symmetric systems or other non-Hermitian quantum systems.