Quantum interference effects in a Λ-type atom interacting with two short laser pulse trains (original) (raw)
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Interference of resonance fluorescence from two four-level atoms
Physical Review A, 1997
In a recent experiment by Eichmann et al., polarization-sensitive measurements of the fluorescence from two four-level ions driven by a linearly polarized laser were made. Depending on the polarization chosen, different degrees of interference were observed. We carry out a theoretical and numerical study of this system, showing that the results can largely be understood by treating the atoms as independent radiators which are synchronized by the phase of the incident laser field. The interference and its loss may be described in terms of the difference between coherent and incoherent driving of the various atomic transitions in the steady-state. In the numerical simulations, which are carried out using the Monte Carlo wave function method, we remove the assumption that the atoms radiate independently and consider the photodetection process in detail. This allows us to see the total interference pattern build up from individual photodetections and also to see the effects of superfluorescence, which become important when the atomic separation is comparable to an optical wavelength. The results of the calculations are compared with the experiment. We also carry out simulations in the non steady-state regime and discuss the relationship between the visibility of the interference pattern and which-path considerations.
Optics Communications, 2014
We investigate the dynamics of a pair of short laser pulse trains propagating in a medium consisting of three-level Λ-type atoms by numerically solving the Maxwell-Schrödinger equations for atoms and fields. By performing propagation calculations with different parameters, under conditions of electromagnetically induced transparency, we compare the propagation dynamics by a single pair of probe and coupling laser pulses and by probe and coupling laser pulse trains. We discuss the influence of the coupling pulse area, number of pulses, and detunings on the probe laser propagation and realization of electromagnetically induced transparency conditions, as well on the formation of a dark state.
Laser-induced transparency and dark-line effects caused by three-wave mixing in atomic systems
Physical Review A, 1997
We study laser-induced transparency and dark-line effects in a two-level atomic system where the upper transition level is coupled by a laser field to a dressed system consisting of two lower-energy metastable states mixed by a second laser field ͑⌸ configuration͒. We show that the emission ͑absorption͒ spectrum of the two-level system develops two dynamic dark lines ͑transparency holes͒ with tunable central frequencies equal to the Rabi frequency of the second field with positive and negative signs, and widths proportional to that of the first field. The detailed evolution of these effects at low-and high-field intensities and the role of quantum interferences are discussed by presenting a model based on laser-induced continuum structure and adopting a dressed-state picture. We discuss various nonlinear processes in this system and show how the dynamics of emission and absorption spectra are determined by one-and two-photon coupling processes.
Photonics Letters of Poland, 2016
We study the propagation dynamics of a single pair of probe and coupling laser pulses in a three-level cascade atomic medium by numerical solving the Maxwell-Bloch equations for atoms and fields. There are investigated influences of pulse duration, intensity and pulse area of a coupling laser on probe laser propagation. We found the conditions when the undistorted probe pulse in such a medium, i.e., the EIT effect, is established. Under EIT conditions, the ground state population is trapped in a dark state.
Resonances in a Three-level Lambda System Excited by an Ultrashort Pulse Train
Latin America Optics and Photonics Conference, 2010
We report on one-and two-photon resonances in a lambda system excited by a train of femtosecond pulses. Numerical results using Bloch equations reveal the conditions to distinguish between optical pumping, Raman and EIT processes. OCIS codes: (270.1670) Coherent optical effects; (320.7150) Ultrafast spectroscopy
Interference-induced splitting of resonances in spontaneous emission
Physical Review A, 2008
We study the resonance fluorescence from a coherently driven four-level atom in the Y-type configuration. The effects of quantum interference induced by spontaneous emission on the fluorescence properties of the atom are investigated. It is found that the quantum interference resulting from cascade emission decays of the atom leads to a splitting of resonances in the excited level populations calculated as a function of light detuning. For some parameters, interference assisted enhancement of inner sidebands and narrowing of central peaks may also occur in the fluorescence spectrum. We present a physical understanding of our numerical results using the dressed state description of the atom-light interaction.
Collisionally-induced quantum interference in resonance fluorescence of two-level atoms [3485-21]
In the experiment with barium vapour (close approximation of a two-level system) we found spectra of resonance fluorescence having the form of a pressure-broadened line with a narrow, not collisionally broadened, dip. They are interpreted as the result of collisionally-induced quantum interference among possible spontaneous emission channels of a dressed atom subjected to stochastic perturbation. Also, the analogy between these effects and the coherent population trapping in three-level systems is pointed out.
Intensity-intensity correlations and quantum interference in a driven three-level atom
Physical Review A, 2000
We investigate the two-time intensity correlation functions of the fluorescence field emitted from a V-type three-level atom. We are particularly interested in the manner in which the atom emits photons in the presence of quantum interference. We show that under strong-field excitation quantum interference leads to anticorrelations of photons emitted from the atomic excited levels which can exist for extremely long times. This indicates that the excited atomic levels are not the preferred radiative states. We find that the atom spends most of its time in a superposition of the excited atomic levels from which it emits strongly correlated photons. The strong correlations are present only for a nonzero splitting between the excited levels, and for degenerate levels the correlations reduce to that of a two-level atom. Moreover, we find that the transition from the ground level to the symmetric superposition of the excited levels does not saturate even for a strong driving field. We also calculate the correlation functions for a weak driving field, and find that in this case the photon correlations are not significantly affected by quantum interference, but the atom can emit a strongly correlated pair of photons produced by a three-wave mixing process. Under appropriate conditions, with near-maximal quantum interference, it is possible to make the maximum value of the correlation function extremely large, in marked contrast with the corresponding case with no quantum interference.