Control of Quantum Information

在这项研究中，我们提出了一个多脉冲控制抑制纯退相的一般公式。该公式没有特定形式的相互作用，用任意系统-储层相互作用的关联函数来表示。我们将该公式应用于一个唯象二能级模型，其中相互作用的关联函数呈指数衰减。在这种情况下，我们的分析表明，多脉冲控制有效地延长了纯退相时间。我们还将该公式应用于自旋-玻色子模型，其中一个自旋与一个玻色子库发生非线性相互作用。我们发现，当脉冲间隔足够短于系统-油藏相互作用的相关时间时，多脉冲控制效果很好。此外，我们发现，通过将脉冲序列施加与水库的动态运动同步，可以有效地抑制退相干。我们抑制了耦合谱密度的形状。我们发现，这一策略的有效性源于水库动力运动的非马尔科夫性质。

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.