ARC Centre for Engineered Quantum System, School of Mathematics and Physics, University of Queensland, Brisbane QLD 4072, Australia.
School of Mathematics and Physics, University of Queensland, Brisbane QLD 4072, Australia.
Phys Rev Lett. 2023 Jan 20;130(3):037001. doi: 10.1103/PhysRevLett.130.037001.
An on-chip microwave circulator that is compatible with superconducting devices is a key element for scale up of superconducting circuits. Previous approaches to integrating circulators on chip involve either external driving that requires extra microwave lines or a strong magnetic field that would compromise superconductivity. Here we report the first proof-of-principle realization of a passive on-chip circulator that is made from a superconducting loop interrupted by three notionally identical Josephson junctions and is tuned with only dc control fields. Our experimental results show evidence for nonreciprocal scattering, and excellent agreement with theoretical simulations. We also present a detailed analysis of quasiparticle tunneling in our device using a hidden Markov model. By reducing the junction asymmetry and utilizing the known methods of protection from quasiparticles, we anticipate that Josephson-loop circulator will become ubiquitous in superconducting circuits.
与超导器件兼容的片上微波环行器是扩展超导电路的关键元件。以前在芯片上集成环行器的方法要么涉及需要额外微波线的外部驱动，要么涉及会损害超导性的强磁场。在这里，我们报告了第一个由三个理论上相同的约瑟夫森结中断的超导环构成的无源片上环行器的原理验证实现，该环行器仅通过直流控制场进行调谐。我们的实验结果表明存在非互易散射，并与理论模拟非常吻合。我们还使用隐马尔可夫模型对我们器件中的准粒子隧道进行了详细分析。通过减小结的不对称性并利用已知的防止准粒子的方法，我们预计约瑟夫森环行器将在超导电路中无处不在。
