超导量子比特中宽带激发光谱揭示的量子环境余辉
Quantum environment afterglow from broadband excitation spectroscopy in superconducting qubits
浏览论文内容
中文总结 AI 辅助
本文通过时间分辨宽带激发光谱研究超导量子比特环境，重建噪声谱并揭示长寿命二能级系统，发现其导致非马尔可夫效应，为容错量子计算提供障碍识别与规避方法。
中文摘要 AI 辅助
理解量子比特环境对于容错超导量子计算至关重要。传统的表征依赖于弛豫过程，而激发过程在很大程度上未被充分探索。在此，我们通过时间分辨宽带激发光谱来获取这一信息。由此得到的量子比特激发光谱揭示了一个高度结构化的景观，其中穿插着冷区域。结合后选择技术，该方法能够完整重建噪声功率谱密度（PSD），并将量子噪声与经典噪声区分开来。利用前馈技术，它揭示了长寿命的二能级系统（TLSs），其弛豫时间跨越数十微秒至毫秒——揭示了量子比特-TLS耦合与TLS弛豫之间的内在联系。数据表明，这些长寿命TLSs是量子比特环境固有的，可能导致持续多个量子比特操作周期的激发。因此，环境保留了对先前动力学的记忆，诸如门保真度等性质变得非马尔可夫且依赖于协议。所提出的方法能够识别并绕过容错量子计算中由长寿命TLSs形成的隐藏障碍。
英文摘要
Understanding the qubit environment is central to fault-tolerant superconducting quantum computation. Characterization typically relies on relaxation, leaving excitation largely underexplored. Here, we access this information with time-resolved broadband excitation spectroscopy. The resulting qubit excitation spectrum reveals a highly structured landscape, interspersed with cold regions. Combined with postselection, this technique enables full reconstruction of the noise power spectral density (PSD) and separates quantum from classical noise. With feed-forward, it exposes long-lived two-level-systems (TLSs), whose relaxation times span tens of microseconds to milliseconds - uncovering an intrinsic link between the qubit-TLS coupling and TLS relaxation. The data suggest that the long-lived TLSs are intrinsic to the qubit environment, and can cause excitation that lasts for many qubit operation cycles. Consequently, the environment retains a memory of prior dynamics, and properties like gate fidelity become non-Markovian and protocol-dependent. The presented approach enables identifying and bypassing the hidden roadblocks formed by long-lived TLSs in fault-tolerant quantum computation.
发表机构
- Institute for Functional Quantum System (PGI-13), Forschungszentrum Jülich（朱利希研究中心功能量子系统研究所）
- Department of Physics, RWTH Aachen University（亚琛工业大学物理系）
机构由 AI 辅助整理，请以论文原文为准。
