Invited review article: The Josephson bifurcation amplifier.
Invited review article: The Josephson bifurcation amplifier.
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DOI：
10.1063/1.3224703
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发表时间：
2009-11
期刊：
影响因子：
--
通讯作者：
R. Vijay;M. Devoret;I. Siddiqi
中科院分区：
文献类型：
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作者：
R. Vijay;M. Devoret;I. Siddiqi
本文综述了约瑟夫森分叉放大器的理论、制作和实现。JBA的核心是一个基于反应性分流约瑟夫森结的非线性振荡器。到放大器的弱输入信号耦合到结临界电流I（0），并导致谐振器等离子体频率ω（p）的色散偏移。通过用足够强的微波电流I（rf）偏置结以进入非线性区域来增强这种移位，其中ω（p）随I（rf）变化。对于驱动频率ω（d）使得ω = 2 Q（1-ω（d）/ω（p））>3，振荡器进入其中可以存在振幅和相位不同的两个非耗散动力学状态O（L）和O（H）的非耗散状态。从O（L）到O（H）的急剧I（0）相关跃迁构成了灵敏数字阈值放大器的基础。在近红外区（Omega<3），连续信号的模拟放大也是可能的。我们提出了表征放大器性能的实验数据，并讨论了两个具体的应用-超导量子比特（数字模式）和色散微波磁强计（模拟模式）的读出。
We review the theory, fabrication, and implementation of the Josephson bifurcation amplifier (JBA). At the core of the JBA is a nonlinear oscillator based on a reactively shunted Josephson junction. A weak input signal to the amplifier couples to the junction critical current I(0) and results in a dispersive shift in the resonator plasma frequency omega(p). This shift is enhanced by biasing the junction with a sufficiently strong microwave current I(rf) to access the nonlinear regime where omega(p) varies with I(rf). For a drive frequency omega(d) such that Omega=2Q(1-omega(d)/omega(p))>3, the oscillator enters the bistable regime where two nondissipative dynamical states O(L) and O(H), which differ in amplitude and phase, can exist. The sharp I(0) dependent transition from O(L) to O(H) forms the basis for a sensitive digital threshold amplifier. In the vicinity of the bistable regime (Omega<3), analog amplification of continuous signals is also possible. We present experimental data characterizing amplifier performance and discuss two specific applications--the readout of superconducting qubits (digital mode) and dispersive microwave magnetometry (analog mode).