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arXiv 0806.4711cond-mat.supr-con
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Josephson相位量子比特Rabi振荡中的多能级效应

Multilevel effects in the Rabi oscillations of a Josephson phase qubit

S. K. Dutta, Frederick W. Strauch, R. M. Lewis, Kaushik Mitra, Hanhee Paik, T. A. Palomaki, Eite Tiesinga, J. R. Anderson, Alex J. Dragt, C. J. Lobb, F. C. Wellstood

摘要:

本文介绍了在一定的微波驱动功率和频率失谐范围内对Nb/AlOx/Nb直流超导量子干涉器件(SQUID)相位量子比特进行拉比振荡测量的结果。考虑到器件的轻微非谐能级结构,几个激发态在量子比特动力学中起重要作用,特别是在高功率下。为了研究这些能级的影响,通过测量器件到电压态的隧穿逃逸率来监测多光子拉比振荡,该隧穿逃逸率对激发态布居特别敏感。我们比较观察到的振荡频率与一个简化的模型构建的全相位量子比特哈密顿量,也比较依赖于时间的逃逸率测量与一个更完整的密度矩阵模拟。良好的定量协议之间的数据和模拟,使我们能够识别共振(类似于交流斯塔克效应),拉比频率的抑制,泄漏到更高的激发态的移位。

英文摘要:

We present Rabi oscillation measurements of a Nb/AlOx/Nb dc superconducting quantum interference device (SQUID) phase qubit with a 100 um^2 area junction acquired over a range of microwave drive power and frequency detuning. Given the slightly anharmonic level structure of the device, several excited states play an important role in the qubit dynamics, particularly at high power. To investigate the effects of these levels, multiphoton Rabi oscillations were monitored by measuring the tunneling escape rate of the device to the voltage state, which is particularly sensitive to excited state population. We compare the observed oscillation frequencies with a simplified model constructed from the full phase qubit Hamiltonian and also compare time-dependent escape rate measurements with a more complete density-matrix simulation. Good quantitative agreement is found between the data and simulations, allowing us to identify a shift in resonance (analogous to the ac Stark effect), a suppression of the Rabi frequency, and leakage to the higher excited states.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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