Quantum Back-Action of an Individual Variable-Strength Measurement
Quantum Back-Action of an Individual Variable-Strength Measurement
复制标题
DOI：
10.1126/science.1226897
复制
发表时间：
2013-01-11
期刊：
影响因子：
56.9
通讯作者：
Devoret, M. H.
中科院分区：
文献类型：
--
作者：
Hatridge, M.;Shankar, S.;Devoret, M. H.
测量量子系统可以随机扰乱其状态。这种反作用的强度和性质取决于测量的数量。在理想设备进行的部分测量中，量子物理学预测系统保持在纯净状态，其演化可以从测量记录中完美追踪。我们使用色散耦合到微波信号穿过的空腔的超导量子位证明了这一特性。观察到两个信号正交的单次测量对量子位状态的反作用，并显示产生随机操作，其作用由测量结果确定。这种对量子位状态的精确监控是量子系统基于测量的反馈控制的重要先决条件。
Measuring a quantum system can randomly perturb its state. The strength and nature of this back-action depend on the quantity that is measured. In a partial measurement performed by an ideal apparatus, quantum physics predicts that the system remains in a pure state whose evolution can be tracked perfectly from the measurement record. We demonstrated this property using a superconducting qubit dispersively coupled to a cavity traversed by a microwave signal. The back-action on the qubit state of a single measurement of both signal quadratures was observed and shown to produce a stochastic operation whose action is determined by the measurement result. This accurate monitoring of a qubit state is an essential prerequisite for measurement-based feedback control of quantum systems.