Generation and protection of steady-state quantum correlations due to quantum channels with memory

Abstract

We have proposed a scheme of the generation and preservation of two-qubit steady-state quantum correlations through quantum channels where successive uses of the channels are correlated. Different types of noisy channels with memory, such as amplitude damping, phase-damping, and depolarizing channels have been taken into account. Some analytical or numerical results are presented. The effect of channels with memory on dynamics of quantum correlations has been discussed in detail. The results show that, steady-state entanglement between two initial qubits without entanglement subject to amplitude damping channel with memory can be generated. The entanglement creation is related to the memory coefficient of channel µ. The stronger the memory coefficient of channel µ is, the more the entanglement creation is, and the earlier the separable state becomes the entangled state. The result also shows that there exists nonlocality in the absence of entanglement. Besides, we compare the dynamics of entanglement with that of quantum discord when a two-qubit system is initially prepared in an entangled state. We show that entanglement dynamics suddenly disappears, while quantum discord displays only in the asymptotic limit. Furthermore, two-qubit quantum correlations can be preserved at a long time in the limit of µ → 1.

Sustainability of entanglement sudden death under the action of memory channel

“…Now, the main issue is to avoid or to delay ESD. When a finite memory is introduced between two consecutive uses of amplitude damping channel, the Kraus operator for two qubit evolution can be constructed as [41], which cannot break into tensor product of 2 × 2 matrix…”

Quantum Correlation in Squeezed Generalized Amplitude Damping Channels with Memory

“…A computation of discord falls into the category of NP-complete problems in general 41 . However, the discord of the X-state can be determined analytically 35,42,43 . Letting , i = 1, 2, 3, 4, be the eigenvalues of the output Werner-like states ρ ± ( t ), the discord of ρ ± ( t ), denoted by , is given bywherewith the Shannon entropy .…”

Variation of quantum speed limit under Markovian and non-Markovian noisy environment

“…Now we will discuss the effect of QSL time on phase damping quantum channel. The Kraus operator for phase damping channels were taken from [17] followed by the condition of non-Markovianity [25]. Due to the presence of memory effect [26][27][28][29][30][31], the ratio of QSL time slowed down upto some extent.…”