增强稳态自旋压缩的理论研究

Theoretical Study of Enhanced Steady-State Spin Squeezing

自旋压缩态是实现高精度量子精密测量和量子信息处理的重要量子资源,如何实现原子自旋的稳态压缩是该研究领域的前沿课题之一.目前,稳态自旋压缩的实现方法主要依赖于原子体系的特殊耗散,研究发现,在单纯耗散体系的某些参数区间内,体系所形成的稳态压缩度非常低.为解决这一问题,提出了一种新的解决方案,即通过在耗散相互作用的基础上增加单轴扭曲非线性演化,可进一步提高量子体系的自旋压缩度,且自旋压缩度增幅极限为3 dB;即使存在噪声的情况下,单轴扭曲演化对体系压缩度的增幅量依旧可达到3 dB,这证明本方案对噪声具有很强的鲁棒性.

Spin squeezed states are important quantum resources for achieving high-precision quantum precise measurement and quantum information processing.How to achieve steady-state squeezing of atomic spin is one of the frontier topics in this research field.Currently,the realization methods of steady-state spin squeezing mainly rely on the special dissipation of atomic systems.In this study,we find that the degree of steady-state squeezing produced by pure dissipative systems is very low in certain parameter ranges.In order to solve this problem,this paper proposes a new scheme to further improve the spin squeezing degree of quantum systems by adding a one-axis twisting nonlinear evolution to the dissipative system,and finds that the increase of the spin squeezing degree is limited to3 dB.It is also found that even in the presence of noise,the increase in the squeezing degree of the system due to the evolution of one-axis twisting can still reach3 dB,which proves that this scheme has strong robustness against noise.