近日，美国量子电路公司的Robert J. Schoelkopf&Kevin S. Chou及其研究团队取得一项新进展。经过不懈努力，他们实现一个具有擦除可检测逻辑测量的超导双轨道腔量子比特。相关研究成果已于2024年7月2日在国际知名学术期刊《自然—物理学》上发表。
在这项工作中，研究人员展示了具有集成擦除检测的双轨道腔量子比特的投影逻辑测量，并测量了量子比特的空转误差。研究人员测量了逻辑状态制备和测量误差在0.01%的水平，并检测到超过99%的腔衰减事件为擦除。研究人员使用该测量协议的精度来区分该系统中不同类型的误差，发现尽管衰减误差发生的概率约为每微秒0.2%，但相位误差发生的频率降低了6倍，比特翻转发生的频率至少降低了150倍。这些发现证实了将双轨腔量子比特连接成高效擦除码所需的预期误差层次结构。
据悉，开发可扩展量子系统的一个关键挑战是在执行操作和测量时纠正累积的误差。众所周知，可以检测到主要误差并将其转换为擦除的系统对量子纠错的要求较低。最近，有人提出，这可以通过在两个超导腔的微波光子态中使用量子信息的双轨道编码来实现。实现这种擦除量子比特的一个必要步骤是提出一种测量方法，并将误差标记为擦除。
附：英文原文
Title: A superconducting dual-rail cavity qubit with erasure-detected logical measurements
Author: Chou, Kevin S., Shemma, Tali, McCarrick, Heather, Chien, Tzu-Chiao, Teoh, James D., Winkel, Patrick, Anderson, Amos, Chen, Jonathan, Curtis, Jacob C., de Graaf, Stijn J., Garmon, John W. O., Gudlewski, Benjamin, Kalfus, William D., Keen, Trevor, Khedkar, Nishaad, Lei, Chan U., Liu, Gangqiang, Lu, Pinlei, Lu, Yao, Maiti, Aniket, Mastalli-Kelly, Luke, Mehta, Nitish, Mundhada, Shantanu O., Narla, Anirudh, Noh, Taewan, Tsunoda, Takahiro, Xue, Sophia H., Yuan, Joseph O., Frunzio, Luigi, Aumentado, Jos, Puri, Shruti, Girvin, Steven M., Moseley, S. Harvey, Schoelkopf, Robert J.
Issue&Volume: 2024-07-02
Abstract: A critical challenge in developing scalable quantum systems is correcting the accumulation of errors while performing operations and measurements. It is known that systems where dominant errors can be detected and converted into erasures have relaxed requirements for quantum error correction. Recently, it has been proposed that this can be achieved using a dual-rail encoding of quantum information in the microwave photon states of two superconducting cavities. One necessary step to realize this erasure qubit is to demonstrate a measurement and to flag errors as erasures. In this work, we demonstrate a projective logical measurement of a dual-rail cavity qubit with integrated erasure detection and measure the qubit idling errors. We measure the logical state preparation and measurement errors at the 0.01% level and detect over 99% of the cavity decay events as erasures. We use the precision of this measurement protocol to distinguish different types of error in this system, finding that although decay errors occur with a probability of approximately 0.2% per microsecond, phase errors occur 6 times less frequently and bit flips occur at least 150 times less frequently. These findings represent a confirmation of the expected error hierarchy necessary to concatenate dual-rail cavity qubits into a highly efficient erasure code.
DOI: 10.1038/s41567-024-02539-4
Source: https://www.nature.com/articles/s41567-024-02539-4