Transmon qubit in a magnetic field: Evolution of coherence and transition frequency
Transmon qubit in a magnetic field: Evolution of coherence and transition frequency
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DOI：
10.1103/physrevresearch.1.023003
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发表时间：
2019-03
影响因子：
4.2
通讯作者：
A. Schneider;T. Wolz;Marco Pfirrmann;M. Spiecker;H. Rotzinger;A. Ustinov;M. Weides
中科院分区：
文献类型：
--
作者：
A. Schneider;T. Wolz;Marco Pfirrmann;M. Spiecker;H. Rotzinger;A. Ustinov;M. Weides
我们报道了固定频率同心跨声子量子比特在外加平面磁场中的光谱和时间域测量，以探索其磁场兼容性的极限。我们证明，即使没有优化的芯片设计或量子比特的材料组合，量子比特的量子相干性也可以达到场值$B={40}，\mathm{mt}$。在较宽的量子比特跃迁频率范围内，退相速率不受磁场的影响。对于量子比特跃迁频率的演化，我们发现在阴影角蒸发过程中产生的意外第二结是不可忽略的，并推导出依赖于场的量子比特能量的解析公式。我们讨论了相关的与场相关的损耗通道，这些通道不能通过我们的测量来区分，从而引发了进一步的理论和实验研究。利用超导量子体系结构中众所周知且经过充分研究的标准组件，我们能够达到与量子传感以及磁自旋和自旋系统的混合应用相关的场区域。
We report on spectroscopic and time-domain measurements on a fixed-frequency concentric transmon qubit in an applied in-plane magnetic field to explore its limits of magnetic field compatibility. We demonstrate quantum coherence of the qubit up to field values of $B={40}\,\mathrm{mT}$, even without an optimized chip design or material combination of the qubit. The dephasing rate $\Gamma_\varphi$ is shown to be not affected by the magnetic field in a broad range of the qubit transition frequency. For the evolution of the qubit transition frequency, we find the unintended second junction created in the shadow angle evaporation process to be non-negligible and deduce an analytic formula for the field-dependent qubit energies. We discuss the relevant field-dependent loss channels, which can not be distinguished by our measurements, inviting further theoretical and experimental investigation. Using well-known and well-studied standard components of the superconducting quantum architecture, we are able to reach a field regime relevant for quantum sensing and hybrid applications of magnetic spins and spin systems.