Dynamics of entanglement protection of two qubits using a driven laser field and detunings: Independent and common, Markovian and/or non-Markovian regimes

Abstract

Preventing quantum entanglement from decoherence effect is of theoretical and practical importance in the quantum information processing technologies. In this regard, we consider the entanglement dynamics of two identical qubits where the qubits which are coupled to two independent (Markovian and/or non-Markovian) as well as a common reservoir at zero temperature are further interacted with a classical driving laser field. Then, we study the preservation of generated two-qubit entanglement in various situations using the concurrence measure. It is shown that by applying the classical driving field and so the possibility of controlling the Rabi frequency, the amount of entanglement of the two-qubit system is improved in the off-resonance condition between the qubit and the central cavity frequencies (central detuning) in both non-Markovian and Markovian reservoirs. While the central detuning has a constructive role, the detuning between the qubit and the classical field (laser detuning) affects negatively on the entanglement protection. The obtained results show that long-living entanglement in the non-Markovian reservoir is more accessible than in the Markovian reservoir. We demonstrate that, in a common reservoir non-zero stationary entanglement is achievable whenever the two-qubit system is coupled to the reservoir with appropriate values of relative coupling strengths.

Dynamics of two levitated nanospheres nonlinearly coupling with non-Markovian environment*

“…This result conflicts with previous works, which declare that the information backflow could preserve those properties rather than damage them. [40][41][42][43] To uncover the reason for this, we plot the trace distance between different initial states 𝒟(ρ 1 , ρ 2 ) in Fig. 4(b) with a random initial state pair where the initial state is the same for red and blue lines.…”

Entanglement instability in the interaction of two qubits with a common non-Markovian environment

“…For the rest of the initial two-qubit states that do not lead to finite values of entanglement in the steady state of the system, effective strategies of entanglement preservation based on the Quantum Zeno effect have been proposed [37]. From the viewpoint of entanglement, a relatively interesting scenario arises when one considers two qubits coupled asymmetrically to a common non-Markovian environment [36][37][38][39][40]. Depending on the choice of the initial two-qubit state, this asymmetry in the coupling strengths between each individual qubit and the environment has been shown to potentially lead to larger two-qubit concurrence values beyond the maximum values obtained in the symmetric coupling case [36][37][38], although exact details on the conditions of observing this enhancement are still under investigation.…”

Dynamical control of population and entanglement for open Λ-type atoms by engineering the environment

“…[43,44] There were many studies on the control of entanglement in dissipative environments, but most of them focused on qubit systems. [45][46][47][48][49] Although a few studies have involved the evolution of entanglement of dissipative V-type atoms, [50,51] similar research for the dissipative Λ-type atoms, without Born-Markov approximation, have not been reported yet. In this paper, based on the exact solution of the open Λ-type atom, we investigate the control of population and entanglement through the engineering of the decay rate and environmental spectral frequency.…”