Pulse propagation, population transfer and light storage in five-level media

We consider adiabatic interaction of five-level atomic systems and their media with four short laser pulses under the condition of all two-photon detunings being zero. We derive analytical expressions for eigenvalues of the system's Hamiltonian and determine conditions of adiabaticity for both the atom and the medium. We analyse, in detail, the system's behaviour when the eigenvalue with non-vanishing energy is realized. As distinct from the usual dark state of a five-level system (corresponding to zero eigenvalue), which is a superposition of three states, in our case the superposition of four states does work. This seemingly unfavourable case is nevertheless demonstrated to imitate completely a three-level system not only for a single atom but also in the medium, since the propagation equations are also split into those for three- and two-level media separately. We show that, under certain conditions, all the coherent effects observed in three-level media, such as population transfer, light slowing, light storage, and so on, may efficiently be realized in five-level media. This has an important advantage that the light storage can be performed twice in the same medium, i.e., the second pulse can be stored without retrieving the first one, and then the two pulses can be retrieved in any desired sequence

Short Pulse Propagation in an Inverted Two-Level Medium

We consider propagation of a pulse carrying optical information in a resonant medium of twolevel atoms and revisit the concept of the group velocity. We obtain conditions when this concept may be used and show that in a population inverted medium the possible superluminal propagation may result in advance times much shorter than the pulse duration because of lethargic amplification following from the complete exact solution of the problem

Short Pulse Propagation in an Inverted Two-Level Medium

We consider propagation of a pulse carrying optical information in a resonant medium of twolevel atoms and revisit the concept of the group velocity. We obtain conditions when this concept may be used and show that in a population inverted medium the possible superluminal propagation may result in advance times much shorter than the pulse duration because of lethargic amplification following from the complete exact solution of the problem

Short Pulse Propagation in an Inverted Two-Level Medium

We consider propagation of a pulse carrying optical information in a resonant medium of twolevel atoms and revisit the concept of the group velocity. We obtain conditions when this concept may be used and show that in a population inverted medium the possible superluminal propagation may result in advance times much shorter than the pulse duration because of lethargic amplification following from the complete exact solution of the problem

Coherent control of interference processes in radiative decays

Possibility of coherent control of spontaneous emission from four- and five-level system in the laser radiation field is studied. The four-level system consists of two levels resonantly driven by laser radiation where either of levels may decay to a separate level. For such a system, we show that the presence of the second decay channel may deteriorate the destructive interference occurring in case of one decay channel because of Autler-Townes effect. The five-level diagram represents two two-level resonantly driven systems with the upper levels decaying to a common level. For this diagram, interference between the two decay channels takes place and it is partially or completely destructive or constructive depending on the initial conditions and on the mutual orientation of the transition dipole moments. It is shown that population transfer takes place by the same quantum vacuum via spontaneous emission. The populations are shown to have damping oscillatory nature

Selective reflection by atomic vapor: experiments and self-consistent theory

Selective reflection of laser radiation from the interface between atomic vapor and a dielectric is studied for a wide range of vapor density. A self-consistent model is developed, some analytical results are obtained, as well as a number of curves are computed that are in good agreement with experimental spectra measured in cesium and rubidium vapor cells.