85 research outputs found
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 aĂ©rea de plantas de crisĂąntemo cultivadas em vaso, em ambiente protegido sob nĂveis de condutividade elĂ©trica.
O presente trabalho foi desenvolvido com o objetivo de avaliar os efeitos de nĂveis de condutividade elĂ©trica, em cultivo protegido como meio de indicar a melhor concentração de sais a serem aplicadas Ă s plantas de crisĂąntemo de forma a suprir a demanda de N, P e K. O experimento foi conduzido no municĂpio de Paranapanema (Holambra II), Estado de SĂŁo 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
Gilberto Freyre e o tempo-espaço brasileiro: uma crĂtica ao cronĂłtopo da modernidade
InfluĂȘncia da mistura de sulfato de amĂŽnio com urĂ©ia sobre a volatilização de nitrogĂȘnio amoniacal
Medida indireta da clorofila e sua relação com o manejo da adubação nitrogenada em plantas cĂtricas fertirrigadas
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