Control of Quantum Information

在这项研究中，我们提出了一个通用公式，以抑制纯减相的多脉冲控制。该公式不受特定形式的相互作用影响，而是用任意系统-油藏相互作用的相关函数表示。我们将该公式应用于一个相互作用的相关函数呈指数衰减的两级模型。在这种情况下，我们分析表明，通过多脉冲控制，可以有效地延长纯消相时间。我们还将该公式应用于自旋-玻色子模型，其中自旋与玻色子库非线性相互作用。我们发现，当脉冲间隔足够短于系统-储备相互作用的相关时间时，多脉冲控制效果良好。此外，我们发现通过将脉冲序列应用与储层的动态运动同步，可以有效地抑制退相干。我们对耦合谱密度的形状进行了抑制。我们发现这种策略的有效性源于水库动力运动的非马尔可夫性质。

In this study, we present a general formulation to suppress pure dephasing by multipulse control. The formula is free from a specific form of interaction and is expressed in terms of the correlation function of arbitrary system-reservoir interaction. We apply the formula to a phenomenological two-level model where the correlation function of the interaction decays exponentially. In this case, we analytically show that the pure dephasing time is effectively lengthened by the multipulse control. We also apply the formula to the spin-boson model where a spin nonlinearly interacts with a boson reservoir. We find the multipulse control works well when the pulse interval is sufficiently shorter than the correlation time of system-reservior interaction. Moreover, we find that the decoherence is effectively suppressed by synchronizing the pulse-train application with the dynamical motion of the reservoir. We suppression on the shape of the coupling spectral density. We find that the effectiveness of this strategy arises from the non-Markovian nature of dynamical motion of the reservoir.