Dissipation in Josephson qubits
Dissipation in Josephson qubits
复制标题
约瑟夫森量子位的耗散
DOI：
10.1007/978-94-007-1021-4_8
复制
发表时间：
2003
期刊：
影响因子：
2.3
通讯作者：
A. Shnirman
中科院分区：
文献类型：
--
作者：
Y. Makhlin;A. Shnirman
约瑟夫森结系统已经被研究为量子比特的潜在实现。对于它们作为量子比特的操作来说，长时间保持量子相位相干性是至关重要的。弛豫和失相效应经常在布洛赫方程的框架中描述。最近的实验证明了1/fnoise的重要性，或者在与噪声源的线性耦合被抑制的点上工作。这需要已知方法和结果的推广和扩展。在本教程中，我们介绍了耗散环境中约瑟夫森量子比特的哈密顿量，并回顾了布洛赫方程的推导以及系统的推广。我们讨论了1/f噪声，噪声源的非线性耦合，以及强脉冲对耗散动力学的影响。这些例子说明了高频噪声谱对量子比特参数的重整化以及低频模式的非指数衰减。
Josephson-junction systems have been studied as potential realizations of quantum bits. For their operation as qubits it is crucial to maintain quantum phase coherence for long times. Frequently relaxation and dephasing effects are described in the frame of the Bloch equations. Recent experiments demonstrate the importance of 1/fnoise, or operate at points where the linear coupling to noise sources is suppressed. This requires generalizations and extensions of known methods and results. In this tutorial we present the Hamiltonian for Josephson qubits in a dissipative environment and review the derivation of the Bloch equations as well as systematic generalizations. We discuss 1/fnoise, nonlinear coupling to the noise source, and effects of strong pulses on the dissipative dynamics. The examples illustrate the renormalization of qubit parameters by the high-frequency noise spectrum as well as non-exponential decay governed by low-frequency modes.