Period-doubling-bifurcation readout for a Josephson qubit
Period-doubling-bifurcation readout for a Josephson qubit
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约瑟夫森量子位的倍周期分岔读数
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Y. Makhlin
中科院分区：
文献类型：
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作者：
A. Zorin;Y. Makhlin
基于外泵浦非线性谐振电路中的参数倍周期分叉，提出了一种具有工作原理的阈值检测器。交流驱动谐振电路包括直流偏置约瑟夫森结，由于其二次非线性，确保了参数频率转换(倍周期分叉)。在驱动器的半频率处的剧烈振荡允许检测到有效电感的微小变化，从而读出耦合约瑟夫森量子比特的量子态。比较了该电路与传统约瑟夫森分叉放大器的分叉特性，并讨论了其可能的优点。
We propose a threshold detector with an operation principle, based on a parametric period-doubling bifurcation in an externally pumped nonlinear resonance circuit. The ac-driven resonance circuit includes a dc-current-biased Josephson junction ensuring parametric frequency conversion (period-doubling bifurcation) due to its quadratic nonlinearity. A sharp onset of oscillations at the half-frequency of the drive allows for detection of small variations of an effective inductance and, therefore, the read-out of the quantum state of a coupled Josephson qubit. The bifurcation characteristics of this circuit are compared with those of the conventional Josephson bifurcation amplifier, and its possible advantages are discussed.