Nonlocal Generalized Quantum Measurements of Spin Products Without Maximal Entanglement
Nonlocal Generalized Quantum Measurements of Spin Products Without Maximal Entanglement
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发表时间：
2019-12
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通讯作者：
P. Vidil;K. Edamatsu
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作者：
P. Vidil;K. Edamatsu
在类空分离的量子系统上测量非定域可观测量是一项资源匮乏且具有实验挑战性的任务。已经提出了几种理论测量方案，以增加其可行性，使用共享的最大纠缠辅助。我们提出了一种新的方法来解决这个问题，使用广义量子测量的语言，表明它实际上是可以测量的非局部自旋产品观察，而不一定需要一个最大纠缠的辅助。这种方法为更经济的任意强度非局部测量打开了大门，其应用范围从非局部弱值到贝尔不等式的可能的新测试。明确了测量强度和所需辅助纠缠量之间的关系，为将量子非定域性、纠缠和信息传输联系在一起的联系带来了新的视角。
Measuring a nonlocal observable on a space-like separated quantum system is a resource-hungry and experimentally challenging task. Several theoretical measurement schemes have already been proposed to increase its feasibility, using a shared maximally-entangled ancilla. We present a new approach to this problem, using the language of generalized quantum measurements, to show that it is actually possible to measure a nonlocal spin product observable without necessarily requiring a maximally-entangled ancilla. This approach opens the door to more economical arbitrary-strength nonlocal measurements, with applications ranging from nonlocal weak values to possible new tests of Bell inequalities. The relation between measurement strength and the amount of ancillary entanglement needed is made explicit, bringing a new perspective on the links that tie quantum nonlocality, entanglement and information transmission together.