Noise suppression via generalized-Markovian processes
Noise suppression via generalized-Markovian processes
复制标题
DOI：
10.1103/physreva.96.052113
复制
发表时间：
2017-11-13
影响因子：
2.9
通讯作者：
Zanardi, Paolo
中科院分区：
文献类型：
--
作者：
Marshall, Jeffrey;Venuti, Lorenzo Campos;Zanardi, Paolo
到目前为止，噪声本身对执行量子信息处理任务是有用的，这一点已经得到了充分的证实。我们给出的结果表明，人们可以通过用另一种形式的噪声抵消其有害影响来有效地降低与噪声量子信道相关的错误率。特别是，我们考虑了在纯马尔科夫(Lindblad)动力学之上添加更一般形式的耗散的效果，我们称之为广义马尔科夫噪声。这种噪声有一个相关的记忆核，由此产生的动力学由一个积分-微分方程式描述。整体动力学的特征是衰减率，它不仅依赖于原始的耗散时间尺度，而且还依赖于新的积分核。我们发现，人们可以设计这个核，从而通过增加这个噪声项来降低总的衰减率。对于裸噪声由退相的Pauli信道描述的情况，我们说明了这种技术。我们对该模型进行了解析求解，结果表明，在达到相同的保真度、纠缠度和误差阈值的情况下，可以有效地将信道长度增加一倍(甚至三倍)。我们用数值方法验证了该方案还可以用来防止模拟自发辐射和激发过程的热马氏噪声(在非零温度下)。讨论了该方案的物理解释，由此附加的广义马尔可夫噪声使系统周期性地与背景马尔可夫噪声解耦。
It is by now well established that noise itself can be useful for performing quantum information processing tasks. We present results which show how one can effectively reduce the error rate associated with a noisy quantum channel by counteracting its detrimental effects with another form of noise. In particular, we consider the effect of adding on top of a purely Markovian (Lindblad) dynamics, a more general form of dissipation, which we refer to as generalized-Markovian noise. This noise has an associated memory kernel and the resulting dynamics are described by an integrodifferential equation. The overall dynamics are characterized by decay rates which depend not only on the original dissipative time scales but also on the new integral kernel. We find that one can engineer this kernel such that the overall rate of decay is lowered by the addition of this noise term. We illustrate this technique for the case where the bare noise is described by a dephasing Pauli channel. We analytically solve this model and show that one can effectively double (or even triple) the length of the channel, while achieving the same fidelity, entanglement, and error threshold. We numerically verify this scheme can also be used to protect against thermal Markovian noise (at nonzero temperature), which models spontaneous emission and excitation processes. A physical interpretation of this scheme is discussed, whereby the added generalized-Markovian noise causes the system to become periodically decoupled from the background Markovian noise.