Decoherence in qubits, caused by their interaction with a noisy environment, poses a significant challenge to the development of reliable quantum processors. A prominent source of errors arises from noise in coupled ancillas, which can quickly spread to qubits. By actively monitoring these noisy ancillas, it is possible to not only identify qubit decoherence events but also to correct these errors in real time. This approach is particularly beneficial for bosonic qubits, where the interaction with ancillas is a dominant source of decoherence. In this work, we uncover the intricate dynamics of decoherence in a superconducting cavity qubit due to its interaction with a noisy transmon ancilla. By tracking the noisy ancilla trajectory and using real-time feedback, we successfully recover the lost coherence of the cavity qubit, achieving a fivefold increase in its pure dephasing time. Additionally, by detecting ancilla errors and converting them into erasures, we improve the pure dephasing time by more than an order of magnitude. These advances are essential for realizing long-lived cavity qubits with high-fidelity gates, and they pave the way for more efficient bosonic quantum error-correction codes. Published by the American Physical Society 2024

中文翻译：

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通过实时反馈恢复耦合到噪声辅助器件的腔体量子比特的量子相干性


量子比特与嘈杂环境的相互作用导致的退相干性对可靠量子处理器的开发构成了重大挑战。一个突出的误差来源来自耦合辅助中的噪声，这些噪声可以迅速传播到量子比特。通过主动监测这些嘈杂的辅助设备，不仅可以识别量子比特退相干事件，还可以实时纠正这些错误。这种方法对玻色子量子比特特别有益，其中与 ancillas 的相互作用是退相干的主要来源。在这项工作中，我们揭示了超导腔量子比特中由于与嘈杂的 transmon ancilla 相互作用而发生的退相干动力学。通过跟踪嘈杂的 ancilla 轨迹并使用实时反馈，我们成功地恢复了空腔量子比特丢失的相干性，使其纯去相时间增加了五倍。此外，通过检测辅助错误并将其转换为擦除，我们将纯移相时间缩短了一个数量级以上。这些进步对于实现具有高保真门的长寿命腔量子比特至关重要，它们为更高效的玻色子量子纠错码铺平了道路。 美国物理学会 2024 年出版