关联退相位有色噪声通道下熵不确定关系的调控

Regulation of entropic uncertainty relation in correlated channels with dephasing colored noise

不确定性原理限制了观察者对两个不相容可观测量的精确测量能力,在量子信息科学领域的量子精密测量中扮演着重要角色.本文研究关联退相位有色噪声通道下两量子比特系统的量子存储支撑熵不确定关系,结合通道连续使用间的关联性和动力学演化中的非马尔科夫性调控熵不确定度及其下限.分别选取最大纠缠态和可分离态作为系统的初态,通过调节关联强度和非马尔科夫性发现:完全关联通道可以最大程度地抑制退相干,降低熵不确定度及其下限,此时非马尔科夫效应不发挥作用;部分关联通道与非马尔科夫效应结合可以在演化中某些时刻更有效地降低熵不确定度及其下限;长时间演化后,系统的熵不确定度及下限达到稳定值,且稳定值只与通道的关联强度有关,通道的关联性越强,稳态的熵不确定度及下限越低.最后分析熵不确定性及其下限降低的物理本质,发现熵不确定度及其下限的降低源于系统量子关联的增加.

The uncertainty principle limits the ability for observer to precisely measure two incompatible observables,and plays a crucial role in quantum precision measurement in the quantum information science.When quantum systems interact with their surroundings,they inevitably result in decoherence,which increases the uncertainty of the system.In the process of quantum information processing,the effective regulation of uncertainty becomes a key problem that needs to be solved.In this work,we investigate the quantum-memory-assisted entropic uncertainty relation of a two-qubit system under correlated channels with dephasing colored noise.We demonstrate that it is possible to control the entropic uncertainty,U,and its lower bound,U_(b),by combining correlations between successive uses of channels and the non-Markovianity of the dynamical evolution.Firstly,the evolutionary characteristics of the trace distance are employed to distinguish between Markovianity and non-Markovianity of the channel.Subsequently,the system is selected to be either a maximally entangled state or separated state initially.By adjusting the strengthηof the correlations,we find that with the increase ofη,the entropic uncertainty and its lower bound decrease.Especially,if the channel is fully correlated(η=1),the entropic uncertainty and its lower bound remain constant under the channel,indicating that decoherence is completely suppressed.A comparison of Markovian channel with non-Markovian channel reveals that the entropic uncertainty and its lower bound exhibit oscillatory behaviour under non-Markovian channels.The combination of correlations and non-Markovianity of the channel demonstrates that the entropic uncertainty and its lower bound can be reduced under fully correlated channels where the non-Markovianity has no effect.This is because fully correlated channels suppress decoherence to a greatest extent.Under partially correlated channels,the combination of correlations and non-Markovianity can more effectively reduce the entropic uncertainty and its lower bound.Under such channels,correlations of the channel reduce the entropic uncertainty and its lower bound during the whole evolution,while the non-Markovianity contributes to their oscillations and reduce them in some specific time.Furthermore,the results show that the entropic uncertainty and its lower bound reach steady values that depend only on the strength of the correlations after long-time evolution.In other words,the stronger the correlations,the lower the entropy uncertainty and its lower bound of steady states will be.Finally,we analyse the physical nature of the decrease of the entropic uncertainty and its lower bound,and it is found that the decrease of the entropic uncertainty and its lower bound originate from the increase of the quantum correlations in the system.