The concepts and ideas of coherent, nonlinear and quantum optics deeply penetrate into the range of 10-100 kiloelectronvolt (keV) photon energies, corresponding to soft gamma-ray (hard xray )) radiation. The recent experimental achievements in this frequency range include demonstration of the parametric down-conversion in the Langevin regime [1], cavity electromagnetically induced transparency [2], collective Lamb shift [3], and single-photon revival in the nuclear absorbing sandwiches [4]. Realization of a single photon coherent storage [5] and stimulated Raman adiabatic passage [6] were recently proposed. Still the number of tools for coherent manipulation of gamma-photon -nuclear ensemble interactions remains rather limited. In this work an efficient method to coherently control the waveforms of gamma-photons has been suggested and verified. In particular, the temporal compression of an individual gamma-photon into coherent ultrashort pulse train has been demonstrated. The method is based on the resonant interaction of gamma-photons with an ensemble of nuclei with modulated frequency of the resonant transition. The frequency modulation, achieved by uniform vibration of the resonant absorber due to the Doppler Effect, results in the time-dependence of the resonant absorption and dispersion, which allow shaping of the incident gamma-photons. The developed technique is expected to give a strong ) It is a historic tradition to call a radiation in this range x-ray radiation when it is produced by electron motion and to call it gamma-ray radiation if it is produced by nuclear transitions. 2impetus on emerging fields of coherent and quantum gamma-optics, providing a basis for realization of the gamma-photon -nuclear ensemble interfaces and quantum interference effects at the nuclear gamma-ray transitions.Quantum optics is the field of research dealing with interactions of quanta of electromagnetic radiation with quantum transitions of matter. It provides the basis for new fast growing fields of quantum cryptography, communication, and information. So far the experiments in these fields have been implemented either with microwave or optical photons, interacting with atomic electron transitions, and typically required cryogenic temperatures. The gamma-photons in the range of 10-100keV and the corresponding nuclear quantum transitions are the most suitable for realization of such experiments due to nearly 100% detector efficiency, extremely high Q-factor (~10 12 for 14.4keV transition in 57 Fe) of recoilless nuclear transitions even at room temperature, existence of radioactive materials (representing themselves the natural sources of single gamma-photons) and the cascade scheme of radiative decay of some radioactive sources (Fig.1a), allowing one to study the photon temporal shape via time-delayed coincidence measurement technique [7]. Moreover, the gamma-photons have important potential advantages over the microwave and optical photons for applications in cryptography, communication and information due to extremely...

We study basic issues central to the storage of quantum information in a coherently prepared atomic medium such as the role of adiabaticity. We also propose and demonstrate transporting, multiplexing, and time reversing of stored light.

We prove that it is possible to freeze a light pulse (i.e., to bring it to a full stop) or even to make its group velocity negative in a coherently driven Doppler broadened atomic medium via electromagnetically induced transparency (EIT). This remarkable phenomenon of the ultraslow EIT polariton is based on the spatial dispersion of the refraction index n(omega,k), i.e., its wave number dependence, which is due to atomic motion and provides a negative contribution to the group velocity. This is related to, but qualitatively different from, the recently observed light slowing caused by large temporal (frequency) dispersion.