Entanglement and non-Markovianity of a multi-level atom decaying in a cavity

The speed of evolution of a qubit undergoing a nonequilibrium environment with spectral density of general ohmic form is investigated. First we reveal non-Markovianity of the model, and find that the non-Markovianity quantified by information backflow of Breuer et al. [Phys. Rev. Lett. 103 210401 (2009)] displays a nonmonotonic behavior for different values of the ohmicity parameter s in fixed other parameters and the maximal non-Markovianity can be achieved at a specified value s. We also find that the non-Markovianity displays a nonmonotonic behavior with the change of a phase control parameter. Then we further discuss the relationship between quantum speed limit (QSL) time and non-Markovianity of the open-qubit system for any initial states including pure and mixed states. By investigation, we find that the QSL time of a qubit with any initial states can be expressed by a simple factorization law: the QSL time of a qubit with any qubitinitial states are equal to the product of the coherence of the initial state and the QSL time of maximally coherent states, where the QSL time of the maximally coherent states are jointly determined by the non-Markovianity, decoherence factor and a given driving time. Moreover, we also find that the speed of quantum evolution can be obviously accelerated in the wide range of the ohmicity parameter, i.e., from sub-Ohmic to Ohmic and super-Ohmic cases, which is different from the thermal equilibrium environment case.

Section: The Non-markovianity Measure and Quantum Speed Limitsmentioning

confidence: 99%

Quantum speed limits of a qubit system interacting with a nonequilibrium environment

He¹,

Yao²,

Li³

et al. 2016

“…For the dynamics of V-type atoms dissipating in zero-temperature environments, the method of finding an exact solution has been discussed. [38,39] For the dissipative dynamics of Λ-type atoms, however, we have not yet found the relevant discussions, even though it has been touched on already. [40] One motivation of this paper is to present the exactly analytical solution for a three-level Λ-type atom dissipating in a zero-temperature Lorentzian environment.…”

Section: Introductionmentioning

confidence: 99%

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

Wang¹,

Ren²,

Zeng³

2019

The exactly analytical solution for the dynamics of the dissipative Λ-type atom in the zero-temperature Lorentzian environment is presented. On this basis, we study the evolution of the population and entanglement. We find that the stable populations on the two lower levels of the Λ-type atom can be effectively adjusted by the combination of the relative decay rate and the environmental spectral frequency. However, for the initial Werner-like state, the stable entanglement between the two Λ-type atoms has very little tunability. Furthermore, the stable entanglement for the bilateral environment case is larger than that of the unilateral environmental case. A nonintuitive relation between the stable entanglement and stable population is found.

“…The quantum Fisher information flow may be employed for distinguishing the Markovian and non-Markovian processes. [10,11] Moreover, in particular, the entanglement revives in the non-Markovian regime [9,[12][13][14][15] and reduced exponentially in the Markovian regime. [16][17][18] In fact, even though Markovian dynamics includes a level of back reaction, it neglects the entanglement that arises between bodies and bath modes during the evolution.…”

Section: Introductionmentioning

confidence: 99%

Dissipative dynamics of an entangled three-qubit system via non-Hermitian Hamiltonian: Its correspondence with Markovian and non-Markovian regimes

Rastegarzadeh¹,

Tavassoly²

2021

We investigate an entangled three-qubit system in which only one of the qubits experiences the decoherence effect by considering a non-Hermitian Hamiltonian, while the other two qubits are isolated, i.e., do not interact with environment, directly. Then, the time evolution of the density matrix (for the pure as well as mixed initial density matrix) and the corresponding reduced density matrices are obtained, by which we are able to utilize the dissipative non-Hermitian Hamiltonian model with Markovian and non-Markovian regimes via adjusting the strange of the non-Hermitian term of the total Hamiltonian of the under-considered system.