Spin Squeezing under Non-Markovian Channels by Hierarchy Equation Method

TL;DR

This paper investigates how spin squeezing in an ensemble of spin-1/2 particles evolves under non-Markovian environmental interactions, revealing phenomena like sudden vanishing and revival of squeezing through an exact hierarchy equation approach.

Contribution

It introduces an exact hierarchy equation method to analyze spin squeezing dynamics in non-Markovian environments without common approximations.

Findings

Spin squeezing exhibits multiple sudden vanishing and revival phenomena.

Lower bath temperatures enhance the revival effects.

Spin squeezing can asymptotically vanish over time.

Abstract

We study spin squeezing under non-Markovian channels, and consider an ensemble of $N$ independent spin-1/2 particles with exchange symmetry. Each spin interacts with its own bath, and the baths are independent and identical. For this kind of open system, the spin squeezing under decoherence can be investigated from the dynamics of the local expectations, and the multi-qubit dynamics can be reduced into the two-qubit one. The reduced dynamics is obtained by the hierarchy equation method, which is a exact without rotating-wave and Born-Markov approximation. The numerical results show that the spin squeezing displays multiple sudden vanishing and revival with lower bath temperature, and it can also vanish asymptotically.