Department of Applied Physics and Physics, Yale University, 401 Becton Center, 15 Prospect Street, New Haven, Connecticut 06520, USA.
Peter Grünberg Institut (PGI-2), Forschungszentrum Jülich, 52425 Jülich, Germany.
Nat Commun. 2014 Dec 18;5:5836. doi: 10.1038/ncomms6836.
Superconducting circuits have attracted growing interest in recent years as a promising candidate for fault-tolerant quantum information processing. Extensive efforts have always been taken to completely shield these circuits from external magnetic fields to protect the integrity of the superconductivity. Here we show vortices can improve the performance of superconducting qubits by reducing the lifetimes of detrimental single-electron-like excitations known as quasiparticles. Using a contactless injection technique with unprecedented dynamic range, we quantitatively distinguish between recombination and trapping mechanisms in controlling the dynamics of residual quasiparticle, and show quantized changes in quasiparticle trapping rate because of individual vortices. These results highlight the prominent role of quasiparticle trapping in future development of superconducting qubits, and provide a powerful characterization tool along the way.
超导电路作为一种有前途的容错量子信息处理候选方案，近年来引起了越来越多的关注。人们一直致力于将这些电路完全屏蔽在外部磁场之外，以保护超导的完整性。在这里，我们展示了涡旋可以通过减少有害的单电子类激发（称为准粒子）的寿命来提高超导量子比特的性能。使用具有前所未有的动态范围的非接触式注入技术，我们定量地区分了在控制残余准粒子动力学中再结合和俘获机制，并且由于单个涡旋而显示出准粒子俘获率的量子化变化。这些结果突出了准粒子俘获在未来超导量子比特发展中的重要作用，并提供了一种强大的特征化工具。
