Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA.
Department of Physics, Yale University, New Haven, Connecticut 06520, USA.
Phys Rev Lett. 2014 Jan 31;112(4):047002. doi: 10.1103/PhysRevLett.112.047002. Epub 2014 Jan 29.
We present microwave measurements of a high quality factor superconducting resonator incorporating two aluminum nanobridge Josephson junctions in a loop shunted by an on-chip capacitor. Trapped quasiparticles (QPs) shift the resonant frequency, allowing us to probe the trapped QP number and energy distribution and to quantify their lifetimes. We find that the trapped QP population obeys a Gibbs distribution above 75 mK, with non-Poissonian trapping statistics. Our results are in quantitative agreement with the Andreev bound state model of transport, and demonstrate a practical means to quantify on-chip QP populations and validate mitigation strategies in a cryogenic environment.
我们展示了一种高质量因数超导谐振器的微波测量结果，该谐振器包含两个铝纳米桥约瑟夫森结，在一个由片上电容器旁路的环路中。被捕获的准粒子（QPs）会改变谐振频率，使我们能够探测被捕获的 QP 数量和能量分布，并量化它们的寿命。我们发现，在 75 mK 以上，被捕获的 QP 群体遵循吉布斯分布，具有非泊松俘获统计。我们的结果与输运的安德烈夫束缚态模型定量一致，并证明了一种在低温环境中定量量化片上 QP 群体和验证缓解策略的实际方法。
