Quantum Decoherence
Quantum Decoherence
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量子退相干
DOI：
10.1007/978-3-7643-7808-0_4
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Ithier G
中科院分区：
文献类型：
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作者：
Ithier G
固态量子位电路（量子位）是实现量子处理器的候选者，它原则上可以执行一些经典顺序处理器无法实现的计算任务。退相干是一个关键问题，因为电路比原子等微观物体更容易发生退相干。我们介绍了不同的固态量子位族，它们要么基于半导体纳米结构中的单粒子态，要么基于超导约瑟夫森电路的全局量子态。我们更详细地讨论了库珀对盒约瑟夫森电路，以及由它衍生的量子电路。在这个器件中，电路与外部电路的去耦策略允许提高量子相干性。我们暴露的量子比特状态的操作上获得的结果在quantronium。我们开发了一个通用的框架来理解量子比特电路中的退相干，并展示了相干时间测量如何允许表征噪声源耦合。
Solid state quantum bit circuits (qubits) are candidates for the implementation of quantum processors, which can in principle perform some computational tasks beyond reach of classical sequential processors. Decoherence is there a key issue since electrical circuits are more prone to decoherence than microscopic objects such as atoms. We introduce the different families of solid state qubits, which are either based on single particle states in semiconductor nanostructures, or on global quantum states of superconducting Josephson circuits. We treat more in detail the Cooper pair box Josephson circuit, and the quantronium circuit derived from it. In this device, a decoupling strategy of the circuit from the outside circuitry allows to improve quantum coherence. We expose results obtained on the manipulation of the qubit state in the quantronium. We develop a general framework for understanding decoherence in qubit circuits, and show how coherence time measurements allow to characterize noise sources coup.