Katz N, Ansmann M, Bialczak Radoslaw C, Lucero Erik, McDermott R, Neeley Matthew, Steffen Matthias, Weig E M, Cleland A N, Martinis John M, Korotkov A N
Department of Physics and California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA.
Science. 2006 Jun 9;312(5779):1498-500. doi: 10.1126/science.1126475.
Measurement is one of the fundamental building blocks of quantum-information processing systems. Partial measurement, where full wavefunction collapse is not the only outcome, provides a detailed test of the measurement process. We introduce quantum-state tomography in a superconducting qubit that exhibits high-fidelity single-shot measurement. For the two probabilistic outcomes of partial measurement, we find either a full collapse or a coherent yet nonunitary evolution of the state. This latter behavior explicitly confirms modern quantum-measurement theory and may prove important for error-correction algorithms in quantum computation.
测量是量子信息处理系统的基本组成部分之一。部分测量，即全波函数坍缩并非唯一结果的情况，为测量过程提供了详细测试。我们在一个展现出高保真单次测量的超导量子比特中引入量子态层析成像。对于部分测量的两种概率性结果，我们发现要么是全坍缩，要么是态的相干但非幺正演化。后一种行为明确证实了现代量子测量理论，并且可能对量子计算中的纠错算法具有重要意义。
