Spin squeezing: Thermal behavior and distribution on excited states

TL;DR

This paper explores how thermal effects influence spin squeezing in a transverse field XY model, revealing temperature-induced transitions and the creation of squeezed states from coherent states at finite temperatures.

Contribution

It provides an exact analysis of thermal and excited state spin squeezing behavior in the XY model, highlighting temperature-induced transitions and state behavior.

Findings

No transition temperature below the thermal factorized field

Transition from thermal squeezed to unsqueezed state at the coherent temperature

Finite temperature can generate squeezed states from zero-temperature coherent states

Abstract

We investigate the spin-squeezing behavior under thermal effects in a one-dimensional transverse field XY model with spin-1/2. The exact solution of the model helps us to compute the spin-squeezing parameter as a function of temperature and also in all excited states with higher energy than the ground state. We find that below the thermal factorized field, h_f(T_{co}), there is no transition temperature. At the thermal factorized field, a transition from a thermal squeezed state to an unsqueezed state occurs at a specific temperature called the coherent temperature. Interestingly, we show that the finite temperature can create squeezed states from a state which at zero temperature is a coherent state. To complete our study, we also analyze the variation of the spin-squeezing parameter in the excited states and provide a behavioral analysis of the thermal spin-squeezing parameter.