Abstract
Quantum technologies able to manipulating single quantum systems, are presently developing. Among the dowries of the quantum realm, entanglement is one of the basic resources for the novel quantum revolution. Within this context, one is faced with the problem of protecting the entanglement when a system state is manipulated. In this paper, we investigate the effect of the classical driving field on the generation entanglement between two qubits interacting with a bosonic environment. We discuss the effect of the classical field on the generation of entanglement between two (different) qubits and the conditions under which it has a constructive role in protecting the initial-state entanglement from decay induced by its environment. In particular, in the case of similar qubits, we locate a stationary sub-space of the system Hilbert space, characterized by states non depending on the environment properties as well as on the classical driving-field. Thus, we are able to determine the conditions to achieve maximally entangled stationary states after a transient interaction with the environment. We show that, overall, the classical driving field has a constructive role for the entanglement protection in the strong coupling regime. Also, we illustrate that a factorable initial-state can be driven in an entangled state and, even, in an entangled steady-state after the interaction with the environment.
Highlights
Quantum technologies able to manipulating single quantum systems, are presently developing
Entanglement is an essential resource in many fields of application for quantum technologies, for instance in quantum cryptography and computation, in teleportation, in the frequency standard improvement problem, and metrology based on quantum phase estimation[1]
We have investigated the analytical dynamics of entanglement for two qubits dissipating into a common environment
Summary
We consider a system in which two qubits with (different) transition frequencies ωj ( j = 1 and 2) are driven by an external classical field. The Hamiltonian describing the whole system in the dipole and rotating wave approximations is written as (we assume = 1). J=1 k j=1 k where σz(j) = |e j e| − g j g is the population inversion operator of the jth qubit with transition frequency ωj , ωL and ωk represent the frequencies of the classical driving field and the cavity quantized modes, respectively. Gk represent the coupling strength of the interactions of the qubits with the classical driving field and the cavity modes, respectively. It should be noted that during the derivation of the effective Hamiltonian (4), the non-conservation energy terms have been neglected according to the rotating-wave approximation[25,26].
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