AI 中文总结
该研究探究了量子比特受关联多轴噪声作用的约化动力学，推导了布洛赫矢量的闭合时间局域方程，发现交叉光谱关联可调制相干性与弛豫，提供控制参数并产生相干性复苏效应。
AI 中文摘要
我们研究了量子比特在与共享玻色库耦合产生的关联纵向和横向噪声作用下的约化动力学。环境涨落由半正定矩阵值谱密度表征，其复非对角元编码了频域中退相位和弛豫通道之间的关联。在二阶时间卷积无规框架内，我们推导了约化密度矩阵布洛赫矢量分量的闭合时间局域方程。数值实现通过精确纯退相位解和已确立的横向耦合自旋-玻色模型行为得到验证。当两个噪声通道同时存在时，交叉光谱项耦合了原本不同的退相位和弛豫区域，产生的动力学无法通过添加独立噪声贡献来重现。特别是，这些关联会产生非单调的布居弛豫，以及相干性初始衰减后的瞬态复苏。交叉光谱的强度、带宽、延迟和相位为这些效应的幅度和时间结构提供了控制参数。我们的结果表明，关联的多轴噪声可在时间上重新分配相干性损失和能量弛豫，从而在弱耦合 regime 内提供增强相干性或抑制弛豫的有限时间窗口。
英文摘要
We investigate the reduced dynamics of a qubit subject to correlated longitudinal and transverse noise arising from its coupling to a shared bosonic bath. The environmental fluctuations are characterized by a positive-semidefinite matrix-valued spectral density, whose complex off-diagonal elements encode correlations between dephasing and relaxation channels in the frequency domain. Within the second-order time-convolutionless framework, we derive closed time-local equations for the Bloch-vector components of the reduced density matrix. The numerical implementation is validated against the exact pure-dephasing solution and the established behavior of the transverse-coupling spin-boson model. When both noise channels are present, the cross-spectral terms couple the otherwise distinct dephasing and relaxation sectors, producing dynamics that cannot be reproduced by adding independent noise contributions. In particular, the correlations generate non-monotonic population relaxation and a transient revival of coherence following its initial decay. The strength, bandwidth, delay, and phase of the cross spectrum provide control parameters for the magnitude and temporal structure of these effects. Our results demonstrate that correlated multi-axis noise can redistribute coherence loss and energy relaxation in time, thereby providing finite temporal windows of enhanced coherence or suppressed relaxation within the weak-coupling regime.
Comments27 pages, 8 figures
