2025-10-20 東京大学
対称性チャネル検証法のイメージ図
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2025-10-20-002
- https://www.t.u-tokyo.ac.jp/hubfs/press-release/2025/1020/002/text.pdf
- https://journals.aps.org/prxquantum/abstract/10.1103/jcd6-lft3
ノイズの多い量子チャネルを浄化するための対称チャネル検証 Symmetric Channel Verification for Purifying Noisy Quantum Channels
Kento Tsubouchi, Yosuke Mitsuhashi, Ryuji Takagi, and Nobuyuki Yoshioka
PRX Quantum Published: 15 October, 2025
DOI: https://doi.org/10.1103/jcd6-lft3
Abstract
Symmetry inherent in quantum states has been widely used to reduce the effect of noise in quantum error correction and a quantum error-mitigation technique known as symmetry verification. However, these symmetry-based techniques exploit symmetry in quantum states rather than quantum channels, limiting their application to cases where the entire circuit shares the same symmetry. In this work, we propose symmetric channel verification (SCV), a channel purification protocol that leverages the symmetry inherent in quantum channels. By introducing different phases to each symmetric subspace and employing a quantum phase estimation-like circuit, SCV can detect and correct symmetry-breaking noise in quantum channels. We further propose a hardware-efficient implementation of SCV at the virtual level, which requires only a single-qubit ancilla and is robust against the noise in the ancilla qubit. Our protocol is applied to various Hamiltonian simulation circuits and phase estimation circuits, resulting in a significant reduction of errors. Furthermore, in setups where only Clifford unitaries can be used for noise purification, which is relevant in the early fault-tolerant regime, we show that SCV under Pauli symmetry represents the optimal purification method.
