Mišta Ladislav, Tatham Richard
Department of Optics, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic.
Phys Rev Lett. 2016 Dec 9;117(24):240505. doi: 10.1103/PhysRevLett.117.240505. Epub 2016 Dec 7.
We introduce a cryptographically motivated quantifier of entanglement in bipartite Gaussian systems called Gaussian intrinsic entanglement (GIE). The GIE is defined as the optimized mutual information of a Gaussian distribution of outcomes of measurements on parts of a system, conditioned on the outcomes of a measurement on a purifying subsystem. We show that GIE vanishes only on separable states and exhibits monotonicity under Gaussian local trace-preserving operations and classical communication. In the two-mode case, we compute GIE for all pure states as well as for several important classes of symmetric and asymmetric mixed states. Surprisingly, in all of these cases, GIE is equal to Gaussian Rényi-2 entanglement. As GIE is operationally associated with the secret-key agreement protocol and can be computed for several important classes of states, it offers a compromise between computable and physically meaningful entanglement quantifiers.
我们引入了一种受密码学启发的二分高斯系统纠缠度量，称为高斯固有纠缠（GIE）。GIE被定义为系统各部分测量结果的高斯分布的优化互信息，条件是对纯化子系统的测量结果。我们证明GIE仅在可分态上消失，并且在高斯局部保迹操作和经典通信下表现出单调性。在双模情况下，我们计算了所有纯态以及几类重要的对称和非对称混合态的GIE。令人惊讶的是，在所有这些情况下，GIE都等于高斯Rényi-2纠缠。由于GIE在操作上与密钥协商协议相关联，并且可以针对几类重要的态进行计算，它在可计算的和具有物理意义的纠缠度量之间提供了一种折衷。
