Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED

We present a way to engineer an effective anti-Jaynes-Cumming and a Jaynes-Cumming interaction between an atomic system and a single cavity mode and show how to employ it in reservoir engineering processes. To construct the effective Hamiltonian, we analyse considered the interaction of an atomic system in a \{Lambda} configuration, driven by classical fields, with a single cavity mode. With this interaction, we firstly show how to generate a decoherence-free displaced squeezed state for the cavity field. In our scheme, an atomic beam works as a reservoir for the radiation field trapped inside the cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401 (2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in high-Q resonators. In our scheme, all the atoms have to be prepared in the ground state and, as in the cited article, neither atomic detection nor precise interaction times between the atoms and the cavity mode are required. From this same interaction, we can also generate an ideal squeezed reservoir for atomic systems. For this purpose we have to assume, besides the engineered atom-field interaction, a strong decay of the cavity field (i.e., the cavity decay must be much stronger than the effective atom-field coupling). With this scheme, some interesting effects in the dynamics of an atom in a squeezed reservoir could be tested

Concentração de N, P e K na parte aérea de plantas de crisântemo cultivadas em vaso, em ambiente protegido sob níveis de condutividade elétrica.

O presente trabalho foi desenvolvido com o objetivo de avaliar os efeitos de níveis de condutividade elétrica, em cultivo protegido como meio de indicar a melhor concentração de sais a serem aplicadas às plantas de crisântemo de forma a suprir a demanda de N, P e K. O experimento foi conduzido no município de Paranapanema (Holambra II), Estado de São Paulo..

Squeezing arbitrary cavity-field states through their interaction with a single driven atom

We propose an implementation of the parametric amplification of an arbitrary radiation-field state previously prepared in a high-Q cavity. This nonlinear process is accomplished through the dispersive interactions of a single three-level atom (fundamental |g>, intermediate |i>, and excited |e> levels) simultaneously with i) a classical driving field and ii) a previously prepared cavity mode whose state we wish to squeeze. We show that, in the adiabatic approximantion, the preparation of the initial atomic state in the intermediate level |i> becomes crucial for obtaing the degenerated parametric amplification process.Comment: Final published versio

Preparation and control of a cavity-field state through atom-driven field interaction: towards long-lived mesoscopic states

The preparation of mesoscopic states of the radiation and matter fields through atom-field interactions has been achieved in recent years and employed for a range of striking applications in quantum optics. Here we present a technique for the preparation and control of a cavity mode which, besides interacting with a two-level atom, is simultaneously submitted to linear and parametric amplification processes. The role of the amplification-controlling fields in the achievement of real mesoscopic states, is to produce highly-squeezed field states and, consequently, to increase both: i) the distance in phase space between the components of the prepared superpositions and ii) the mean photon number of such superpositions. When submitting the squeezed superposition states to the action of similarly squeezed reservoirs, we demonstrate that under specific conditions the decoherence time of the states becomes independent of both the distance in phase space between their components and their mean photon number. An explanation is presented to support this remarkable result, together with a discussion on the experimental implementation of our proposal. We also show how to produce number states with fidelities higher than those derived as circular states