A. Vidiella-Barranco

Interaction of superpositions of coherent states of light with two-level atoms

Abstract We investigate some of the basic features of the interaction of superpositions of coherent states of light with two-level atoms in the framework of the Jaynes-Cummings model. We compare the behaviour of the system in the case of having a coherent superposition state and a statistical mixture of coherent states as an initial field. We investigate the collapses and revivals of the atomic inversion by studying the evolution of the Q function of the cavity field. We also establish the connection between the purity of the field and the collapses and revivals of the atomic inversion.

Interaction of Squeezed Light with Two-level Atoms

Abstract We investigate some of the fundamental features of the interaction of squeezed light with two-level atoms in the framework of the Jaynes-Cummings model. We start our analysis by calculating the collapses and revivals of the atomic inversion. We discuss the degree of purity of the field (given by the entropy) and its disentanglement from the atomic source. The connection with the evolution of the Q-function is also made. We notice that contrary to the coherent state case, the field turns into a nearly pure (squeezed) state at the revival time as if the field was prepared in a coherent state. The field also becomes a superposition of squeezed states at half of the revival time, and this is confirmed by investigating the photon number distribution. The phase properties of the field are discussed using the Pegg-Barnett formalism.

Cluster-type entangled coherent states

We present the cluster-type entangled coherent states (CTECS) and discuss their properties. A cavity QED generation scheme using suitable choices of atom-cavity interactions, obtained via detunings adjustments and the application of classical external fields, is also presented. After the realization of simple atomic measurements, CTECS representing nonlocal electromagnetic fields in separate cavities can be generated.

Quantum state reconstruction in the presence of dissipation

Abstract We propose a realistic scheme to determine the quantum state of a single-mode cavity field even after it has started to decay due to the coupling with an environment. Although dissipation destroys quantum coherences, we show that at zero temperature enough information about the initial state remains, in an observable quantity, to allow the reconstruction of its Wigner function. 42.50.-p, 03.65.Bz, 42.50.Dv.

Long-time-scale revivals in ion traps

In this paper we investigate the interaction of a single ion in a trap with laser beams. Our approach, based on unitary transformating the Hamiltonian, allows its exact diagonalization without performing the Lamb-Dicke approximation. We obtain a transformed Jaynes-Cummings-type Hamiltonian, and we demonstrate the existence of super-revivals in that system.

The entanglement of two dipole–dipole coupled atoms in a cavity interacting with a thermal field

We investigate the entanglement properties of a system of two dipole–dipole coupled two-level atoms resonantly interacting with a thermal field in a high-Q cavity. We obtain the evolution operator for this system in an analytical form, and use it to evaluate the atom–atom entanglement through the calculation of the negativity. We find that, despite the destructive effect of thermal noise, the dipole interaction yields a considerable amount of entanglement between the two atoms.

Entanglement between motional states of a single trapped ion and light

We propose a generation method of Bell-type states involving light and the vibrational motion of a single trapped ion. The trap itself is supposed to be placed inside a high-

Field purification in the intensity-dependent Jaynes-Cummings model

Q

Nonextensive approach to decoherence in quantum mechanics

cavity sustaining a single mode, quantized electromagnetic field. Entangled light-motional states may be readily generated if a conditional measurement of the ions internal electronic state is made after an appropriate interaction time and a suitable preparation of the initial state. We show that all four Bell states may be generated using different motional sidebands (either blue or red), as well as adequate ionic relative phases.

On the Interaction of Two-level Atoms with Superpositions of Coherent States of Light

Abstract We have found that, in the intensity-dependent Jaynes-Cummings model, a field initially prepared in a statistical mixture of two coherent states, |α〉 and | − α〉, evolves toward a pure state. We have also shown that an even-coherent state turns periodically into a rotated odd-coherent state during the evolution.