Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117, Heidelberg, Germany.
Department of Physics, National Central University, 32001 Taoyuan City, Taiwan.
Sci Rep. 2016 Sep 19;6:33361. doi: 10.1038/srep33361.
Heralded entanglement between macroscopical samples is an important resource for present quantum technology protocols, allowing quantum communication over large distances. In such protocols, optical photons are typically used as information and entanglement carriers between macroscopic quantum memories placed in remote locations. Here we investigate theoretically a new implementation which employs more robust x-ray quanta to generate heralded entanglement between two crystal-hosted macroscopical nuclear ensembles. Mössbauer nuclei in the two crystals interact collectively with an x-ray spontaneous parametric down conversion photon that generates heralded macroscopical entanglement with coherence times of approximately 100 ns at room temperature. The quantum phase between the entangled crystals can be conveniently manipulated by magnetic field rotations at the samples. The inherent long nuclear coherence times allow also for mechanical manipulations of the samples, for instance to check the stability of entanglement in the x-ray setup. Our results pave the way for first quantum communication protocols that use x-ray qubits.
宏观样本之间的 heralded 纠缠是当前量子技术协议的重要资源，允许在远距离进行量子通信。在这样的协议中，光学光子通常被用作远程放置的宏观量子存储器之间的信息和纠缠载体。在这里，我们从理论上研究了一种新的实现方案，该方案使用更稳健的 X 射线量子对两个晶体承载的宏观核系综之间产生 heralded 纠缠。两个晶体中的 Mössbauer 核与 X 射线自发参量下转换光子集体相互作用，在室温下产生具有约 100 ns 相干时间的 heralded 宏观纠缠。通过在样品上旋转磁场，可以方便地操纵纠缠晶体之间的量子相位。固有长核相干时间还允许对样品进行机械操作，例如检查 X 射线设置中纠缠的稳定性。我们的结果为使用 X 射线量子位的第一个量子通信协议铺平了道路。
