The possibility of using a solid medium to store few-photon laser pulses as coupled excitations between light and matter is investigated. The role of inhomogeneous broadening and nonadiabaticity are considered, and conditions governing the feasibility of the scheme are derived. The merits of a number of classes of solid are examined.
We theorize a quantum memory based on the dark-state polariton field, formed by the superposition of atomic and photonic states of a travelling probe laser pulse under the application of standing wave modes of a dominant control laser pulse using a lambda-level scheme Electromagnetically Induced Transparency in a solid medium. We show how an enhancement in the storage time for the pulse is achieved by eliminating pulse broadening due to diffusion. At last, we propose an experiment that can help realize the storage of a probe pulse in the hyperfine levels 3H4↔1D2 of Pr3+:Y2SiO5, cryogenically cooled at 4.5 K. We also discuss multiple applications the storage of the quantum states the probe pulse with a prolonged time interval must have.
We investigate theoretically the coupling of a cavity mode to a continuous distribution of emitters. We discuss the influence of the emitters' inhomogeneous broadening on the existence and on the coherence properties of the polaritonic peaks. We find that their coherence depends crucially on the shape of the distribution and not only on its width. Under certain conditions the coupling to the cavity protects the polaritonic states from inhomogeneous broadening, resulting in a longer storage time for a quantum memory based on emitter ensembles. When two different ensembles of emitters are coupled to the resonator, they support a peculiar collective dark state, which is also very attractive for the storage of quantum information.
We consider slow-light propagation in an atomic medium with a tripod level scheme. We show that the coexistence of two types of dark-state polaritons leads to the propagation dynamics, which is qualitatively different from that in a $\mathrm{\ensuremath{\Lambda}}$ medium, and allows therefore for very efficient conversion of signal photons into spin excitations. This efficiency is shown to be very close to 1 even for very long signal light pulses, which could not be entirely compressed into a $\mathrm{\ensuremath{\Lambda}}$ medium at a comparable strength of the control field.
Coherent interactions of laser light with atomic ensembles allow one to modify dispersive properties of a medium and lead to new optical phenomena. Studies of the controlled light propagation and storing in such media have recently become a dynamically developing field of research motivated both by the fundamental character of the processes and by potential applications. This article briefly reviews basic theoretical approach to the dynamics of the propagation of laser pulses in optically modified media. The method and the physical processes are discussed that allow one to slow down the group velocity of laser pulse to zero (stopping of light), to transfer the state of a light pulse to atomic coherences and to restore the pulse. The interpretation of these phenomena in the formalism of dark-state polaritons is presented. Examples of possible coherent manipulations on a stored light are also discussed.
In this paper, we derive an expression for the dark-state polariton field, formed by the superposition of atomic and photonic states, for the case of a travelling probe laser pulse under the application of a standing wave control laser pulse for a lambda-level scheme EIT System in a solid crystal. We show how an enhancement in the nonlinearity of the EIT process by eliminating pulse broadening due to diffusion can be achieved in the case of a travelling probe pulse under the effect of standing wave control laser pulses. At last, we propose an experiment that can help realise the storage of a probe pulse in the hyperfine levels 3 H 4 ↔ 1 D 2 of Pr 3+ : Y 2 SiO 5, cryogenically cooled at 4.5 K. We, at last, predict from the temporal variation of the energy density of the stored probe pulse that a longer storage time of the travelling probe pulse is possible for a perfect standing wave control laser field than a non-standing control wave, due to its more prominent nonlinear effect.
We study the possibility to store and retrieve quantum information with use of “dark” and ”bright” polaritons in solids with excitonic resonances. In a crystal with Λ-type impurity atoms the upper level lying in the excitonic band of the crystal forms a Fano-type resonant state via configuration interaction with the continuum of crystal’s excitonic band. Polariton states are introduced in case of transitions through excitonic resonance and the properties of these states are studied. We also investigate propagation of dark polariton and show that its shape and quantum state are preserved during propagation. Limiting cases of adiabatic and non-adiabatic turning-on the fields are analyzed in detail.