标题： 超导量子比特在高磁场中的自旋环境 显示英文标题

标题： Spin Environment of a Superconducting Qubit in High Magnetic Fields

摘要： 具有量子非破坏性读出和主动反馈的超导量子位可用于作为信息引擎，以探测和操控微观自由度，无论这些自由度是故意设计的还是在环境中自然出现的。 在自旋系统的情况下，所需的磁场偏置对超导体和约瑟夫森结构成了挑战。 在这里，我们展示了具有对超过一特斯拉磁场具有鲁棒性的能谱和相干性的颗粒铝纳米结通量子量子位（gralmonium）。 扫描磁场揭示了一个顺磁自旋-1/2集合，当电子自旋共振与量子位匹配时，这是gralmonium的主要损耗机制。 我们还观察到在磁场中快速通量噪声的抑制，这表明表面自旋被冻结。 使用主动状态稳定序列，量子位对环境中的长寿命两能级系统（TLSs）进行超极化，这些系统之前被认为可能是自旋。 令人惊讶的是，这些TLSs的耦合不受磁场影响，从而留下了它们起源的问题。 gralmonium在特斯拉磁场下的稳健运行为探索自旋环境动力学中的未解问题提供了新机会，并促进了将超导量子位与自旋系统连接的混合架构。 显示英文摘要

摘要： Superconducting qubits equipped with quantum non-demolishing readout and active feedback can be used as information engines to probe and manipulate microscopic degrees of freedom, whether intentionally designed or naturally occurring in their environment. In the case of spin systems, the required magnetic field bias presents a challenge for superconductors and Josephson junctions. Here we demonstrate a granular aluminum nanojunction fluxonium qubit (gralmonium) with spectrum and coherence resilient to fields beyond one Tesla. Sweeping the field reveals a paramagnetic spin-1/2 ensemble, which is the dominant gralmonium loss mechanism when the electron spin resonance matches the qubit. We also observe a suppression of fast flux noise in magnetic field, suggesting the freezing of surface spins. Using an active state stabilization sequence, the qubit hyperpolarizes long-lived two-level systems (TLSs) in its environment, previously speculated to be spins. Surprisingly, the coupling to these TLSs is unaffected by magnetic fields, leaving the question of their origin open. The robust operation of gralmoniums in Tesla fields offers new opportunities to explore unresolved questions in spin environment dynamics and facilitates hybrid architectures linking superconducting qubits with spin systems.