Sudden vanishing of spin squeezing under decoherence

TL;DR

This paper demonstrates that spin squeezing, a measure of quantum correlations in many-body systems, can abruptly disappear under decoherence, revealing a phenomenon called spin-squeezing sudden death (SSSD).

Contribution

It analytically shows the occurrence of SSSD in many-body systems under different decoherence channels and identifies conditions where it does not occur.

Findings

Spin squeezing can suddenly vanish at different times under decoherence.

SSSD is generally caused by decoherence effects.

Some initial states avoid SSSD in amplitude-damping channels.

Abstract

In order to witness multipartite correlations beyond pairwise entanglement, spin-squeezing parameters are analytically calculated for a spin ensemble in a collective initial state under three different decoherence channels. It is shown that, in analogy to pairwise entanglement, the spin squeezing described by different parameters can suddenly become zero at different vanishing times. This finding shows the general occurrence of sudden vanishing phenomena of quantum correlations in many-body systems, which here is referred to as spin-squeezing sudden death (SSSD). It is shown that the SSSD usually occurs due to decoherence and that SSSD never occurs for some initial states in the amplitude-damping channel. We also analytically obtain the vanishing times of spin squeezing.