论文标题
通过初始探针 - 环境相关性提高环境参数的估计
Improving the estimation of environment parameters via initial probe-environment correlations
论文作者
论文摘要
已经提出了小型，可控的量子系统，称为量子探针，以估计表征复杂系统（例如量子系统环境）的各种参数。这些探针以某种初始状态制备，可以与环境相互作用，随后的测量结果揭示了有关表征环境的不同数量的信息，例如系统 - 环境耦合强度，截止频率和温度。这些估计通常是通过仅考虑探测器发生腐烂的方式来做出的。但是，我们表明，有关环境的信息也通过探测态制备之前存在的探针和环境相关性印在探测器上。然后，这些信息可用于改善我们对任何环境的估计。由于谐波振荡器环境，我们将此一般结果应用于经过纯dephasing的两级系统探测器的特定情况，以表明确实可以获得量子渔民信息的急剧增加，因此确实可以获得我们的估计值的精度。我们还考虑将周期性对照脉冲应用于探针以表明两者的组合 - 对照脉冲的效果以及初始相关性 - 可以通过数量级来增加量子渔民信息。
Small, controllable quantum systems, known as quantum probes, have been proposed to estimate various parameters characterizing complex systems such as the environments of quantum systems. These probes, prepared in some initial state, are allowed to interact with their environment, and subsequent measurements reveal information about different quantities characterizing the environment such as the system-environment coupling strength, the cutoff frequency, and the temperature. These estimates have generally been made by considering only the way that the probe undergoes decoherence. However, we show that information about the environment is also imprinted on the probe via the probe and environment correlations that exist before the probe state preparation. This information can then be used to improve our estimates for any environment. We apply this general result to the particular case of a two-level system probe undergoing pure dephasing, due to a harmonic oscillator environment, to show that a drastic increase in the quantum Fisher information, and hence the precision of our estimates, can indeed be obtained. We also consider applying periodic control pulses to the probe to show that with a combination of the two - the effect of the control pulses as well as the initial correlations - the quantum Fisher information can be increased by orders of magnitude.
