Group of Applied Physics, University of Geneva, Geneva, Switzerland.
Phys Rev Lett. 2011 Jun 24;106(25):250404. doi: 10.1103/PhysRevLett.106.250404.
We consider the problem of determining whether genuine multipartite entanglement was produced in an experiment, without relying on a characterization of the systems observed or of the measurements performed. We present an n-partite inequality that is satisfied by all correlations produced by measurements on biseparable quantum states, but which can be violated by n-partite entangled states, such as Greenberger-Horne-Zeilinger states. In contrast to traditional entanglement witnesses, the violation of this inequality implies that the state is not biseparable independently of the Hilbert space dimension and of the measured operators. Violation of this inequality does not imply, however, genuine multipartite nonlocality. We show more generically how the problem of identifying genuine tripartite entanglement in a device-independent way can be addressed through semidefinite programming.
我们考虑了在不依赖于对所观测系统或所进行测量的描述的情况下，确定实验中是否产生了真正的多体纠缠的问题。我们提出了一个 n 分体不等式，它被所有由双可分量子态上的测量产生的相关所满足，但可以被 n 分体纠缠态，如 GHZ 态所违反。与传统的纠缠见证不同，这个不等式的违反意味着该态不是双可分的，而与希尔伯特空间维度和所测量的算子无关。然而，这个不等式的违反并不意味着真正的多体非局域性。我们更一般地展示了如何通过半定规划以设备独立的方式来识别真正的三方纠缠。
