Easy Monitored Entangled States

We discuss the generation and monitoring of durable atomic entangled state via Raman-type process, which can be used in the quantum information processing.Comment: 9 pages, 2 figures, the previous title "Durable Entanglement in Atomic Systems" is replaced by new title, accepted to Appl. Phys. Let

Quantum phase via the angular momentum

Cataloged from PDF version of article.An approach to the quantum phase, taking into account the process of light generation and extending in this way the operational approach, is proposed. The cosine and sine operators of the phase difference of the two circularly polarized modes are determined with the aid of a polar decomposition of the angular momentum of radiative transition and conservation of the total angular momentum. Application of the approach to the Jaynes-Cummings model for an electric dipole transition shows consistency with the classical definition of the phase difference and with the results of standard operational approach as well

Quantification of entanglement via uncertainties

We show that entanglement of pure multi-party states can be quantified by means of quantum uncertainties of certain basic observables through the use of measure that has been initially proposed in [10] for bipartite systems.Comment: Changed content, references added 7 pages, no figures, PRA in pres

Steady state entanglement of two atoms created by classical driving field

The stabilization of steady state entanglement caused by action of a classical driving field in the system of two-level atoms with the dipole interaction accompanied by spontaneous emission is discussed. An exact solution shows that the maximum amount of concurrence that can be achieved in Lamb-Dicke limit is 0.43, which corresponds to the entanglement $\mathcal{E}_{max}=0.285$ ebit. Dependence of entanglement on interatomic distance and classical driving field is examined numerically.Comment: 14 pages, 2 figure

Detecting squeezed phonons through an indirect radiative transition

Cataloged from PDF version of article.A model of the effect of the longitudinal optical phonon number distribution on the Rabi oscillations of the photons involved in the associated indirect transition in a semiconductor is presented. It is shown that a faster cavity photon revival rate is obtained given an initial squeezed thermal phonon state. This is the result of pairwise correlations of phonons due to squeezing and also holds true when phonons are in squeezed vacuum or in squeezed number states; It may be possible to use this effect to detect squeezing in phonons. (C) 1997 American Institute of Physics

Radiation phase and Stokes parameters

Cataloged from PDF version of article.The approach which has been proposed by one of us [Optics Comm. 136 (1997) 219] is developed. The quantum phase properties of radiation are determined via the conservation of the angular momentum in the interaction with a source. It is shown that the use of two dual representations of the angular momentum of the dipole transition leads to the definition of five operators similar in some sense to the Stokes operators of the radiation. The approach is compared with that by Pegg and Barnett [20]. (C) 1998 Elsevier Science B.V