Department of Theoretical Physics, University of Lodz, Pomorska 149/153, 90-236, Łódź, Poland.
Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna, Austria.
Sci Rep. 2023 Jul 11;13(1):11189. doi: 10.1038/s41598-023-38217-3.
Bound entanglement, in contrast to free entanglement, cannot be distilled into maximally entangled states by two local observers applying measurements and utilizing classical communication. In this paper we ask whether a relativistic observer classifies states according to being separable, bound or free entangled in the same manner as an unboosted observer. Surprisingly, this turns out not to be the case. And that even if the system in a given inertial frame of reference is separable with respect to the partition momenta versus spins. In detail, we show that if the spin state is initially bound entangled, some boosted observers observe their spin states to be either bound entangled, separable or free entangled. This also explains why a general measure of the entanglement property is difficult to find.
束缚纠缠与自由纠缠相反，两个本地观察者通过测量和利用经典通信，不能将其提炼成最大纠缠态。在本文中，我们询问相对论观察者是否以与非加速观察者相同的方式对可分离、束缚或自由纠缠的状态进行分类。令人惊讶的是，事实并非如此。即使在给定的惯性参考系中，相对于动量与自旋的划分，系统是可分离的。具体来说，我们表明，如果初始时自旋态是束缚纠缠的，那么一些加速观察者观察到他们的自旋态是束缚纠缠、可分离或自由纠缠的。这也解释了为什么很难找到一个通用的纠缠性质度量。
