School of Mathematical Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Phys Rev Lett. 2014 Jan 10;112(1):010401. doi: 10.1103/PhysRevLett.112.010401. Epub 2014 Jan 6.
We investigate the genuine multipartite nonlocality of three-mode Gaussian states of continuous variable systems. For pure states, we present a simplified procedure to obtain the maximum violation of the Svetlichny inequality based on displaced parity measurements, and we analyze its interplay with genuine tripartite entanglement measured via Rényi-2 entropy. The maximum Svetlichny violation admits tight upper and lower bounds at fixed tripartite entanglement. For mixed states, no violation is possible when the purity falls below 0.86. We also explore a set of recently derived weaker inequalities for three-way nonlocality, finding violations for all tested pure states. Our results provide a strong signature for the nonclassical and nonlocal nature of Gaussian states despite their positive Wigner function, and lead to precise recipes for its experimental verification.
我们研究了连续变量系统三模高斯态的真正多体非局域性。对于纯态，我们提出了一种简化的方法，基于位移奇偶测量来获得 Svetlichny 不等式的最大违反，并分析了它与通过 Renyi-2 熵测量的真正三体纠缠之间的相互作用。在固定三体纠缠的情况下，最大 Svetlichny 违反允许有严格的上限和下限。对于混合态，当纯度低于 0.86 时，不可能违反。我们还研究了一组最近推导出的用于三方非局域性的较弱不等式，发现所有测试的纯态都存在违反。尽管高斯态的 Wigner 函数为正，但我们的结果为其非经典和非局域性质提供了强有力的特征，并为其实验验证提供了精确的方法。
