Single‐Atom Entanglement for a System of Directly Linked Two Cavities in the Presence of an External Classical Field: Effect of Atomic Coherence

Abstract

AbstractThe Hamiltonian of a system composed of two standard Jaynes‐Cummings cells connected by the overlap of evanescent cavity fields, which allows photons to hop from the first cavity to the second and vice versa, and interacting with an external classical field, is simplified in the framework of unitary canonical transformations. James's method of the effective Hamiltonian is used in the derivation of two effective Hamiltonians with two completely dispersive regimes. Analytical expressions for the time dependent wavefunction and the elements of the reduced atomic operators for the different Hamiltonians are derived. The temporal evolution of atomic quantum entropy is calculated when the fields are initially in their vacuum states with various forms of the atomic initial states. Effects of the photon hopping strength, detuning and the various forms of the atomic initial states on the evolution of the von Neumann entropies are analyzed. The impact of the time‐average technique on the features resulting due to involving the controlling parameters and their influences on the considered functions is discussed. Damping is taken into account through a non‐Hermitian Hamiltonian and results are discussed. General conclusions reached are illustrated by numerical results.