Suppression of Crosstalk in Superconducting Qubits Using Dynamical Decoupling
Suppression of Crosstalk in Superconducting Qubits Using Dynamical Decoupling
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DOI：
10.1103/physrevapplied.18.024068
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发表时间：
2021-08
影响因子：
4.6
通讯作者：
Vinay Tripathi;Huo Chen;M. Khezri;K. Yip;E. Levenson-Falk;Daniel A. Lidar
中科院分区：
文献类型：
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作者：
Vinay Tripathi;Huo Chen;M. Khezri;K. Yip;E. Levenson-Falk;Daniel A. Lidar
目前可用的超导量子处理器具有相互连接的transmon量子位元，具有噪声并且容易产生各种错误。这些误差可归因于开放量子系统效应和伪量子比特间耦合（串扰）等来源。在固定频率传输体系结构中，量子比特之间的zz耦合总是存在的，并且会导致相干和非相干串扰误差。因此，它的抑制是利用传输提高量子计算保真度的关键一步。在这里，我们提出了使用动态解耦来抑制串扰，并通过在几个IBM量子云处理器上进行的实验证明了该方案的成功。特别是，我们展示了量子存储器的改进以及单量子比特和双量子比特门操作的性能。我们对多量子位处理器进行了开放量子系统模拟，结果与实验结果吻合良好。我们基于一个简单的解析模型分析了协议的性能，并阐明了量子比特驱动频率在解释结果中的重要性。特别地，我们证明了XY4动态解耦序列在驱动频率小于系统池耦合强度时失去其通用性。我们的工作表明，动态解耦是抑制串扰和开放系统效应的一种有效而实用的方法，从而为基于transmons的量子计算机的高保真度逻辑门铺平了道路。
Currently available superconducting quantum processors with interconnected transmon qubits are noisy and prone to various errors. The errors can be attributed to sources such as open quantum system effects and spurious inter-qubit couplings (crosstalk). The ZZ-coupling between qubits in fixed frequency transmon architectures is always present and contributes to both coherent and incoherent crosstalk errors. Its suppression is therefore a key step towards enhancing the fidelity of quantum computation using transmons. Here we propose the use of dynamical decoupling to suppress the crosstalk, and demonstrate the success of this scheme through experiments performed on several IBM quantum cloud processors. In particular, we demonstrate improvements in quantum memory as well as the performance of single-qubit and two-qubit gate operations. We perform open quantum system simulations of the multi-qubit processors and find good agreement with the experimental results. We analyze the performance of the protocol based on a simple analytical model and elucidate the importance of the qubit drive frequency in interpreting the results. In particular, we demonstrate that the XY4 dynamical decoupling sequence loses its universality if the drive frequency is not much larger than the system-bath coupling strength. Our work demonstrates that dynamical decoupling is an effective and practical way to suppress crosstalk and open system effects, thus paving the way towards higher-fidelity logic gates in transmon-based quantum computers.