Jeong Hayoung, Kim Youngdu, Choi Beomgyu, Cho Minkyun, Woo Seungwook, Chong Yonuk, Lee Yong-Ho, Yeo Hwan-Seop
Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong-gu, Daejeon, 34113, Republic of Korea.
SKKU Advanced Institute of Nano Technology(SAINT), Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Sci Rep. 2025 May 28;15(1):18698. doi: 10.1038/s41598-025-02370-8.
Dynamical decoupling (DD) is a well-established technique for protecting quantum systems from environmental noise. DD effectively mitigates decoherence in superconducting quantum computing systems, where precise implementation plays a crucial role in optimizing its performance. This study investigates how DD implementation timing and sequence design critically affect spectator-induced dephasing from adjacent qubits. We find that excited states of adjacent qubits dramatically degrade operational qubit coherence. We demonstrate that DD sequences applied to adjacent qubits effectively suppress this dephasing. This protection persists even when adjacent qubits remain in superposition states during the sequence. Through systematic characterization of Carr-Purcell-Meiboom-Gill (CPMG) sequences, we show that implementation timing strongly impacts protection effectiveness. While optimal timing achieves substantial coherence enhancement, improper sequence delays can severely degrade protection. Our results highlight the importance of precise timing control for implementing DD in optimizing multi-qubit quantum circuits.
动态解耦（DD）是一种成熟的用于保护量子系统免受环境噪声影响的技术。DD有效地减轻了超导量子计算系统中的退相干，在该系统中精确实施对于优化其性能起着至关重要的作用。本研究调查了DD的实施时机和序列设计如何严重影响相邻量子比特引起的旁观者退相。我们发现相邻量子比特的激发态会显著降低操作量子比特的相干性。我们证明应用于相邻量子比特的DD序列能有效抑制这种退相。即使在序列期间相邻量子比特保持叠加态，这种保护仍然存在。通过对 Carr-Purcell-Meiboom-Gill（CPMG）序列的系统表征，我们表明实施时机强烈影响保护效果。虽然最佳时机可实现显著的相干增强，但不适当的序列延迟会严重降低保护效果。我们的结果突出了在优化多量子比特量子电路中精确控制实施DD时机的重要性。
