标题： 一种用于表面码的酉编码器 显示英文标题

标题： A Unitary Encoder for Surface Codes

摘要： 表面码是容错量子计算的一个有前景的候选方案，并已在许多量子硬件平台上实现。 在这项工作中，我们提出了一种新的非局域幺正电路，用于基于旋转表面码和常规表面码之间的码转换来编码表面码态，这将已知最快的编码器的门计数减半。 虽然幺正编码器可以用来增加码距，但故障距离保持不变。 然而，它们可用于空间-时间高效实现表面码算符的本征态，而这些本征态无法通过横向方式轻松访问，例如Pauli Y本征态和Clifford本征态。 预计非局域电路中的错误传播会使解码比局域幺正编码电路更具挑战性。 然而，我们发现并非如此，并且传统的匹配解码器可以有效使用。 此外，我们进行了数值模拟，以基准测试我们的编码器与先前的局域幺正编码器以及基于稳定子测量的传统编码器在准备Pauli Y本征态方面的性能，发现我们的编码器可以在实验相关的噪声条件下优于这些编码器。 因此，我们的编码器在非局域相互作用可用的平台（如中性原子和囚禁离子）中提供了实际优势。 显示英文摘要

摘要： The surface code is a promising candidate for fault-tolerant quantum computation and has been implemented in many quantum hardware platforms. In this work, we propose a new non-local unitary circuit to encode a surface code state based on a code conversion between rotated and regular surface codes, which halves the gate count of the fastest encoder known previously. While the unitary encoders can be used to increase the code distance, the fault-distance remains fixed. Nonetheless, they can be used for space-time efficient realization of eigenstates of the surface code operators that can't be easily accessed transversally such as the Pauli Y-eignestate and Clifford eigenstates. It may be expected that error propagation in the non-local circuit will make decoding more challenging compared to local unitary encoding circuits. However, we find this not to be the case and that conventional matching decoders can be effectively used. Furthermore, we perform numerical simulations to benchmark the performance of our encoder against a previous local unitary encoder and the conventional stabilizer-measurement based encoder for preparing the Pauli Y-eigenstate and find that our encoder can outperform these in experimentally relevant noise regimes. Therefore, our encoder provides practical advantage in platforms where non-local interactions are available such as neutral atoms and trapped ions.