论文标题
通过字符随机基准测试估算CX门的偏差
Estimating the bias of CX gates via character randomized benchmarking
论文作者
论文摘要
最近的工作表明，只要有人可以实施保留偏见的受控门（CX）门，就可以为偏置噪声量子置质量误差校正。已经提出了几个有偏见的Qubit平台，最著名的是Kerr猫的偏见CX大门。但是，在实验上测量噪声偏差是具有挑战性的，因为它需要在存在更大的状态制备和测量（垃圾邮件）错误的情况下准确估算某些低概率的Pauli错误。在本文中，我们引入了偏置随机基准测试（BRB），作为测量量子门偏置的技术。像所有RB协议一样，BRB非常准确，不受垃圾邮件错误的影响。我们的第一个协议CX二二核BRB是测量整个CX二二核组偏置的直接方法。我们的第二个方案是交错的偏置随机基准测试（IBRB），是针对实验约束偏向噪声量子的交错的RB的概括。这是一个更涉及的程序，它直接针对CX门的偏置。我们的BRB程序占据了仅估计平均忠诚度的经典RB协议和层析成像RB协议之间的中间立场，这些协议提供了更详细的噪声表征，但需要更多的测量以及不一定在有偏见的噪声量子中获得的实验能力。
Recent work has demonstrated that high-threshold quantum error correction is possible for biased-noise qubits, provided one can implement a controlled-not (CX) gate that preserves the bias. Bias-preserving CX gates have been proposed for several biased-noise qubit platforms, most notably Kerr cats. However, experimentally measuring the noise bias is challenging as it requires accurately estimating certain low-probability Pauli errors in the presence of much larger state preparation and measurement (SPAM) errors. In this paper, we introduce bias randomized benchmarking (BRB) as a technique for measuring bias in quantum gates. BRB, like all RB protocols, is highly accurate and immune to SPAM errors. Our first protocol, CX-dihedral BRB, is a straightforward method to measure the bias of the entire CX-dihedral group. Our second protocol, interleaved bias randomized benchmarking (IBRB), is a generalization of interleaved RB tailored to the experimental constraints biased-noise qubits; this is a more involved procedure that directly targets the bias of the CX gate alone. Our BRB procedures occupy a middle ground between classic RB protocols that only estimate the average fidelity, and tomographic RB protocols that provide more detailed characterization of noise but require more measurements as well as experimental capabilities that are not necessarily available in biased-noise qubits.
