28 research outputs found
Changes in the statistical and quantum features of the cavity radiation of a two-photon coherent beat laser due to phase fluctuation
Detailed derivation of the master equation and the corresponding time
evolution of the cavity radiation of a coherent beat laser when the atoms are
initially prepared in a partial coherent superposition is presented. It turns
out that the quantum features and intensity of the cavity radiation are
considerably modified by the phase fluctuation arising due to the practical
incapability of preparing atoms in the intended coherent superposition. New
terms having an opposite sign with the contribution of the driving radiation
emerged in the master equation. This can be taken as an indication for a
competing effect between the two in the manifestation of the nonclassical
features. This, on the other hand, entails that there is a chance for regaining
the quantum properties that might have lost due to faulty preparation by
engineering the driving mechanism and vice versa. In light of this, quite
remarkably, the cavity radiation is shown to exhibit nonclassical features
including two-mode squeezing and entanglement when there is no driving and if
the atoms are initially prepared in a partial maximum atomic coherence
superposition, contrary to earlier predictions for the case of perfect
coherence.Comment: 8 pages and no figur
Effects of decoherence on the radiative and squeezing properties in a coherently driven trapped two-level atom
Analysis of the effects of decoherence on the radiative and squeezing
properties of a coherently driven two-level atom trapped in a resonant cavity
applying the corresponding master equation is presented. The atomic dynamics as
well as the squeezing and statistical properties of the emitted radiation are
investigated. It is found that the atom stays in the lower energy level more
often at steady state irrespective of the strength of the coherent radiation
and thermal fluctuations entering the cavity. Moreover, a strong external
coherent radiation results the splitting of the line of the emission spectrum,
whereas the decoherence broadens the width and significantly decreases the
height. It is also found that the emitted radiation exhibits photon
anti-bunching, super-Poissonian photon statistics and squeezing, despite the
presence of the decoherence which is expected to destroy the quantum features.Comment: 9 pages, 9 figure
Effect of phase fluctuation and dephasing on the dynamics of entanglement generation in a correlated emission laser
A detailed study of the effects of phase fluctuation and dephasing on the
dynamics of the entanglement generated from a coherently pumped correlated
emission laser is presented. It is found that the time evolution of the
entanglement is significantly reliant on the phase fluctuation and dephasing,
particularly, at early stages of the lasing process. In the absence of external
driving radiation, the degree of entanglement and intensity turns out to attain
a maximum value just before starting to exhibit oscillation which dies at
longer time scale. However, in case the driving mechanism is on, the
oscillatory nature disappears due to the additional induced coherent
superposition and the degree of entanglement would be larger at steady state.
Moreover, the degree of entanglement as predicted by the logarithmic negativity
and the Duan-Giedke-Cirac-Zoller criteria exhibits a similar nature when there
is no driving radiation, although such a trend is eroded with increasing
strength of the pumping radiation at longer time scale. The other important
aspect of the phase fluctuation and dephasing is the possibility of relaxing
the time at which the maximum entanglement is detected.Comment: 10 pages, 10 figure