Entanglement Dynamics in a Model Tripartite Quantum System

Abstract

A system comprising a Λ-type or V-type atom interacting with two radiation fields exhibits, during its dynamical evolution, interesting optical phenomena such as electromagnetically-induced transparency (EIT) and a variety of nonclassical effects. Signatures of the latter are seen in the entanglement dynamics of the atomic subsystem and in appropriate field observables. Some of these effects have been experimentally detected, and have even been used to change the nonlinear optical properties of certain atomic media. It is therefore useful to investigate the roles played by specific initial states of the radiation fields, detuning parameters, field nonlinearities and the nature of field-atom couplings on EIT and on the entanglement between subsystems. We investigate these aspects in the framework of a simple model that captures the salient features of such tripartite entangled systems. Entanglement dynamics is shown to be very sensitive to the intensity-dependent atom-field couplings. Unexpected interesting features pertaining to the collapses and revivals of the atomic subsystem von Neumann entropy appear. These features could, in principle, be useful in enabling entanglement.

Recurrence network analysis in a model tripartite quantum system

“…We first consider |α| 2 = 25. As reported earlier [6], the mean photon number exhibits an interesting bifurcation cascade as κ is varied from 0 to 1 (Fig. 2).…”

“…For instance, the changes with time of the quadrature squeezing and entropic squeezing of the state of the system or that of a subsystem have been determined directly from relevant tomograms [4,5]. Sudden death of the entanglement between subsystems [3], as well as the collapse of the entanglement to a constant non-zero value over a significant time-interval [5,6], have been identified theoretically in multipartite models of radiation fields interacting with atomic media. In the examples considered, the full system is an isolated quantum system in a pure state that evolves unitarily under a self-adjoint Hamiltonian.…”

“…In Ref. [6], the dynamics of a tripartite system comprising a Λ-atom interacting with two radiation fields with inherent nonlinearities and field-atom IDC has been investigated. For initially unentangled field and atom states, the subsequent state of the system has been shown to exhibit the full range of nonclassical effects mentioned * pradip@physics.iitm.ac.in above.…”

Estimation of entanglement in bipartite systems directly from tomograms

“…The last of the foregoing is an important step in exploiting tomograms, as entanglement is an essential resource in quantum information processing. In this context it is important to consider interesting phenomena such as sudden death and birth of entanglement [10], and its collapse to a constant non-zero value over a significant interval of time [11], as have been found in model systems. Since we are directly concerned with quantum entanglement indicators here, we recall some standard measures of entanglement between the two subsystems A and B of a bipartite system.…”

Nonclassical effects in optomechanics: dynamics and collapse of entanglement

“…In [25], this last form of IDC between a V or Λ atom and two radiation fields (that mediate allowed transitions between the two pairs of atomic states) has been shown to lead to the occurrence, during dynamical evolution, of a bifurcation cascade that is very sensitive to the precise value of κ. More significantly, it enables collapse of a specific bipartite entanglement to a non-zero value over a significant time interval during the system's temporal evolution.…”