近日，美国芝加哥大学的H. Bernien及其研究小组取得一项新进展。经过不懈努力，他们利用旁观者量子比特（spectator qubits）阵列实现了相干相位误差的中间电路纠正。相关研究成果已于2023年5月25日在国际权威学术期刊《科学》上发表。

该研究小组利用铯旁观者量子比特阵列对铷数据量子比特阵列的相干相误差进行纠正。通过顺序读出、数据处理和前馈操作的组合，这些相干误差在量子电路执行过程中被有效地抑制。该协议适用于各种量子信息平台，并为扩展中性原子量子处理器提供了关键工具，包括中间电路读出原子阵列、实时处理、前馈操作以及相干的中间电路重新加载原子量子比特。

据悉，将易于出错的量子处理器进行规模扩展是一项巨大的挑战。虽然量子纠错最终能够实现容错操作，但所需的量子比特超额和误差阈值令人望而却步。在一个互补的方案中，共位的辅助“旁观者”量子比特充当噪声的原位探针，实现对数据比特错误的实时、相干修正。

附：英文原文

Title: Mid-circuit correction of correlated phase errors using an array of spectator qubits

Author: K. Singh, C. E. Bradley, S. Anand, V. Ramesh, R. White, H. Bernien

Issue&Volume: 2023-05-25

Abstract: Scaling up invariably error-prone quantum processors is a formidable challenge. Although quantum error correction ultimately promises fault-tolerant operation, the required qubit overhead and error thresholds are daunting. In a complementary proposal, co-located, auxiliary ‘spectator’ qubits act as in-situ probes of noise, and enable real-time, coherent corrections of data qubit errors. We use an array of cesium spectator qubits to correct correlated phase errors on an array of rubidium data qubits. By combining in-sequence readout, data processing, and feed-forward operations, these correlated errors are suppressed within the execution of the quantum circuit. The protocol is broadly applicable to quantum information platforms, and establishes key tools for scaling neutral-atom quantum processors: mid-circuit readout of atom arrays, real-time processing and feed-forward, and coherent mid-circuit reloading of atomic qubits.

DOI: ade5337

Source: https://www.science.org/doi/10.1126/science.ade5337