The authors survey the theoretical and experimental aspects of generation of slow light in a far-off-resonance Raman medium driven by a strong coupling field. When material dispersion is negligible, the propagation of two coupled sidebands can be described in terms of two normal modes that propagate independently at different group velocities, one at the vacuum speed of light and one at a reduced velocity. They use solid hydrogen as a Raman medium to demonstrate the generation of slow light. The numerical calculations and experimental observations show that, due to high density, narrow Raman width, and small two-photon detuning, far-off-resonance Raman scattering in solid hydrogen can slow down the pulse-peak velocity of the Stokes and anti-Stokes fields to the order of c/10000. This velocity reduction affects the amplitudes of the Stokes and anti-Stokes fields via the beating between the normal modes. The double-peak structure observed in the intensity temporal profiles of the sideband fields is a signature of the splitting of the copropagating normal modes.
Abstract A practical approach to understanding light scattering processes in the condensed phase is presented. First a theoretical discussion of the various parameters in resonance light scattering is given and there is a special emphasis on our simplified approach to this question. As with other approaches the two level density matrix in association with a quantum regression theorem leads to two types of emission from an ensemble of molecules at finite temperature (T2 ≠ 2T1). We have called one of these fluorescence and the other sharper emission Raman scattering because it results directly from the presence of a coherent polarization in the medium. A brief discussion of time dependent scattering is also given. An experiment that reproduces the main features of the theory is described for resonance scattering from azulene in naphthalene at 30 K. For all values of the laser frequency (near resonance) both a sharp (Raman) and diffuse (fluorescent) component occurs in the emission spectrum. These spectra when interpreted by the simplified theory yield a value of T2 = 0.7 ps from fluorescence linewidth, and T2 = 0.8 ps from the incoherent to coherent scattering ratio, for the 0–0 two level system of azulene in naphthalene. A discussion of practical aspects of the influence of inhomogeneous line broadening is also presented.
Motivated by recent experimental investigations of Cs-Cs-Li Efimov resonances, this work theoretically investigates the few-body properties of $N\ensuremath{-}1$ noninteracting identical heavy bosons, which interact with a light impurity through a large
s-wave scattering length. For Cs-Cs-Cs-Li, we predict the existence of universal four-body states with energies
E4(n,1) and
E4(n,2), which are universally linked to the energy
E3(n) of the
nth Efimov trimer. For infinitely large $^{133}\mathrm{Cs}\text{\ensuremath{-}}^{6}\mathrm{Li}$ and vanishing $^{133}\mathrm{Cs}\text{\ensuremath{-}}^{133}\mathrm{Cs}$ scattering lengths, we find $({E}_{4}^{(1,1)}/{E}_{3}^{(1)}{)}^{1/2}\ensuremath{\approx}1.51$ and $({E}_{4}^{(1,2)}/{E}_{3}^{(1)}{)}^{1/2}\ensuremath{\approx}1.01$. The $^{133}\mathrm{Cs}\text{\ensuremath{-}}^{6}\mathrm{Li}$ scattering lengths at which these states merge with the four-atom threshold, the dependence of these energy ratios on the mass ratio between the heavy and light atoms, and selected aspects of the generalized Efimov scenario for
N>4 are also discussed. Possible implications of our results for ongoing cold atom experiments are presented.