Nonlinear coupler operating on Werner-like states—entanglement creation, its enhancement, and preservation

Abstract

We discuss a model of two nonlinear Kerr-like oscillators, mutually coupled and excited by parametric process. We show that the system's evolution, starting from Werner-like states, remains closed within a small set of two-mode n-photon states the system, and pure two-qubit entangled state can be generated. For some initial Werner-like states delayed entanglement generation can be observed. We investigate the influence of two damping mechanisms on the system's evolution. We show that for the both cases, the entanglement can survive despite the presence of damping, and the effects of sudden entanglement death and its rebirth can appear in the system.

Asymmetry of Quantum Correlations Decay in Nonlinear Bosonic System

“…Such systems are well known as the potential sources of maximally or almost maximally entangled states. Various types of coupling and external driving have already been discussed [26][27][28]32]. In all of those cases it appeared that it was possible to restrict the evolution of the whole coupled system to several bosonic states only-therefore, under the assumptions of weak interactions (as compare with the nonlinearity), truncation of the appropriate wave function was possible.…”

“…In many papers the limited number of two-mode states is the starting point of the discussion of entanglement formation. Such possibility was reported for example in papers dealing with nonlinear quantum scissors, which exploited strongly nonlinear media (with χ (3) much larger than other parameters describing the interactions) to obtain 2-qubit, qutrit-qubit or 2-qutrit systems [26][27][28]. Various external driving mechanisms were also analyzed: continuous excitation, performed by a laser field [24,26]; intense optical field generating two modes by parametric down-conversion process [27].…”

Entanglement versus quantum degree of polarization

“…The states | Ψ ± are the well-known N00N states [31,32], while the other two states | Φ ± have recently been considered in Ref. [33].…”

Enhancement of the entanglement generation via randomly perturbed series of external pulses in a nonlinear Bose–Hubbard dimer

“…In quantum optics, such systems are usually referred to as nonlinear coupler and were proposed in 1982 by Jensen [24] and Maȋer [25]. Kerr-like couplers were intensively investigated (see [26][27][28] and the references quoted therein), and numerous features in such systems have been observed and discussed, including sub-Poissonian and squeezed light [29][30][31][32][33][34] or quantum entanglement generation [35][36][37][38]. It should be emphasized that the Bose-Hubbard model we propose is general enough to describe various physical systems in which the phenomenon of quantum entanglement can be observed.…”

“…As it was mentioned above, quantum entanglement can be generated in Bose-Hubbard systems involving at least two nonlinear oscillators. The discussion of such features was presented in [35][36][37][38]. In those studies, the time between two subsequent pulses was arbitrarily chosen and assumed to be constant.…”