论文标题
由于被困的准颗粒而导致的超导量子设备的两级系统
Two-level systems in superconducting quantum devices due to trapped quasiparticles
论文作者
论文摘要
实施大型超导量子电路的一个主要问题是与界面的两级系统缺陷（TLS）的相互作用，导致量子放松并阻碍某些频率范围内也会漂移的量子操作。另一个主要挑战来自非平衡准粒子（QP），导致量子降低和放松。在这项工作中，我们表明此类QP也可以作为TLS的来源。使用TLS诱导的频率可调谐振器中波动的光谱和时间映射，我们确定了一部分TLS总体的一部分，这些子集是高度相干的TLS，其重新配置温度$ \ sim $ 300 mk和状态的不均匀密度。如果这些TL是由QP形成的，可以理解这些特性，该QP被困在超导级参数参数$δ$的空间波动形成的浅子段状态中。这样的TLS的磁场测量结果揭示了与超导性的联系。我们的结果表明，被困的QP可以诱导Qubit放松。
A major issue for the implementation of large scale superconducting quantum circuits is the interaction with interfacial two-level system defects (TLS) that leads to qubit relaxation and impedes qubit operation in certain frequency ranges that also drift in time. Another major challenge comes from non-equilibrium quasiparticles (QPs) that result in qubit dephasing and relaxation. In this work we show that such QPs can also serve as a source of TLS. Using spectral and temporal mapping of TLS-induced fluctuations in frequency tunable resonators, we identify a subset of the general TLS population that are highly coherent TLS with a low reconfiguration temperature $\sim$ 300 mK, and a non-uniform density of states. These properties can be understood if these TLS are formed by QPs trapped in shallow subgap states formed by spatial fluctutations of the superconducting order parameter $Δ$. Magnetic field measurements of one such TLS reveals a link to superconductivity. Our results imply that trapped QPs can induce qubit relaxation.
