Atomic coherence

About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.

Generation of dipole squeezing in a two-mode system with entangled coherent states of a quantized electromagnetic field

Abstract: Two-mode quantized electromagnetic fields can be entangled and admit a large number of coherent states. In this paper, we consider a two-mode system that consists of a two-level atom interacting with a two-mode quantized electromagnetic field, which is initially prepared in an entangled two-mode coherent state, via a nondegenerate two-photon process in a lossless cavity. We study the quantum fluctuations in the two-mode system and investigate in detail the effects of detuning, Stark shift and atomic coherence on atomic dipole squeezing (ADS). We show that ADS strongly depends on the atomic coherence. It is found that the stronger the correlations between the two modes are involved, the more the ADS could be generated. The detuning or Stark shift has a destructive effect on ADS, but the combined effect of the detuning and Stark shift may lead to a regular, periodical and strong ADS pattern.

Effects of neighboring transitions on the mechanisms of electromagnetically induced absorption and transparency in an open degenerate multilevel system

Abstract: In this study, optical Bloch equations with and without neighboring hyperfine states near the degenerate two-level system (DTLS) in the challenging case of [Formula: see text]Rb D2 transition, which involves the Doppler broadening effect, are solved. The calculated spectra agree well with the experimental results obtained based on the coupling-probe scheme with orthogonal linear polarizations of the coupling and probe fields. The mechanisms of electromagnetically induced absorption (electromagnetically induced transparency) for the open [Formula: see text] and 3 transitions (open [Formula: see text] and 3 transitions) are determined to be the effect of the strong closed [Formula: see text] transition line (strong closed [Formula: see text] transition line); this finding is based on a comparison between the calculated absorption profiles of the DTLS without neighboring states and those of all levels with neighboring states, depending on the coupling and probe power ratios. Furthermore, based on the aforementioned comparison, the crucial factors that enhance or reduce the coherence effects and lead to the transformation between electromagnetically induced absorption and electromagnetically induced transparency, are (1) the power ratios between the coupling and probe beams, (2) the openness of the excited state, and (3) effects of the neighboring states due to Doppler broadening in a real atomic system.

Entanglement between two atoms in the presence of dipole-dipole interaction and atomic coherence

Abstract: We have investigated the influence of dipole-dipole interaction and initial atomic coherence on dynamics of two-atom systems. We have considered a model, in which only one atom is trapped in a cavity, and the other one can be spatially moved freely outside the cavity. We have shown the possibility of disappearance of the entanglement sudden death effect in the presence of the dipole interaction of atoms. We have also derived that the initial atomic coherence can be used for effective control of the degree of the atom-atom entanglement.

Coherent effects on Rabi splitting and multiphoton absorption in an atomic tripod driven by two coupling fields

Abstract: A detailed analytical description of a Doppler-free probe response (absorption and dispersion) is presented for a coherently prepared four-level atomic tripod driven by two coupling fields. Under the density matrix formalism the field-dependent and field-independent coherence are introduced through the off-diagonal matrix elements. Field-dependent coherence appears due to the interference between the probability amplitudes of finding the atom in energy levels associated with the allowed transition, while field-independent phases measure the atomic coherence for a coherently prepared lower state triplet. The double-control coherent effects on the probe response are investigated by controlling the relative driving contribution (coherence) of the two coupling fields, whereas the driving contribution can be controlled by the use of field-independent coherence, along with two coupling parameters like Rabi frequency and detuning of the respective coupling field. We report on the possibility of modifying the Rabi splitting into a perfect electromagnetically induced transparent window at probe resonance by a coherent double-control mechanism in an on-resonance coupling situation. Moreover, for off-resonance coupling, we exhibit the enhancement of multiphoton (two- or three-photon) absorption via coherent control of multiresonance processes.

Atomic coherence in nondegenerate four-wave mixing

Abstract: Two-photon resonant nondegenerate four-wave mixing (NFWM) with the addition of a coupling field in Ba atomic vapour has been studied. We find that coherence of the atomic level transitions leads to suppression of the NFWM signal, giving rise to a dip with a linewidth that is linearly proportional to the intensity of the coupling field.