论文标题
开放量子系统的保护性测量
Protective measurement of open quantum systems
论文作者
论文摘要
我们研究了在存在环境和破坏的情况下保护性量子测量。我们考虑了在测量过程中与自旋环境相互作用的保护测量量子的模型。我们研究了与环境的耦合如何影响保护性测量的两个特性属性，即（i）离开系统状态近似不变的能力，以及（ii）有关期望值的信息传递到设备指针。我们发现，即使与环境的相互作用足够弱，也不会导致初始量子状态的明显退积，也会在测量结束时对设备指针的位置的概率分布显着扩大。从指针位置进行的清洗量至关重要的是可以从指针的读数中测量所需期望值的准确性。我们还表明，即使选择与环境的耦合使系统的状态不受破坏性的影响，环境仍然可能会对指针读数产生不利影响。
We study protective quantum measurements in the presence of an environment and decoherence. We consider the model of a protectively measured qubit that also interacts with a spin environment during the measurement. We investigate how the coupling to the environment affects the two characteristic properties of a protective measurement, namely, (i) the ability to leave the state of the system approximately unchanged and (ii) the transfer of information about expectation values to the apparatus pointer. We find that even when the interaction with the environment is weak enough not to lead to appreciable decoherence of the initial qubit state, it causes a significant broadening of the probability distribution for the position of the apparatus pointer at the conclusion of the measurement. This washing out of the pointer position crucially diminishes the accuracy with which the desired expectation values can be measured from a readout of the pointer. We additionally show that even when the coupling to the environment is chosen such that the state of the system is immune to decoherence, the environment may still detrimentally affect the pointer readout.
