All optical quantum storage based on spatial chirp of the control field

We suggest an all-optical quantum memory scheme which is based on the off-resonant Raman interaction of a signal quantum field and a strong control field in a three-level atomic medium in the case, when the control field has a spatially varying frequency across the beam, called a spatial chirp. We show that the effect of such a spatial chirp is analogous to the effect of a controllable reversible inhomogeneous broadening (CRIB) of the atomic transition used in the gradient echo memory (GEM) scheme. However, the proposed scheme does not require temporal modulation of the control field or the atomic levels, and can be realized without additional electric or magnetic fields. It means that materials demonstrating neither linear Stark nor Zeeman effects can be used and/or materials which are placed in specific external fields remain undisturbed

Quantum storage based on the control field angular scanning

Continuous change of the propagation direction of a classical control field in the process of its off-resonant Raman interaction with a weak signal field in a three-level atomic medium is suggested for quantum storage of a single-photon wave packet. It is shown that due to phase matching condition such an angular control allows one to reversibly map the single-photon wave packet to the Raman spatial coherence grating. Thus, quantum storage and retrieval can be realized without using inhomogeneous broadening of the atomic transitions or manipulating the amplitude of the control field. Under some conditions the proposed scheme proves to be mathematically analogous to the quantum storage scheme based on controlled reversible inhomogeneous broadening of the atomic states.Comment: 9 pages, 4 figure

Superradiant control of gamma-ray propagation by vibrating nuclear arrays

The collective nature of light interactions with atomic and nuclear ensembles yields the fascinating phenomena of superradiance and radiation trapping. We study the interaction of gamma rays with a coherently vibrating periodic array of two-level nuclei. Such nuclear motion can be generated, e.g., in ionic crystals illuminated by a strong driving optical laser field. We find that deflection of the incident gamma beam into the Bragg angle can be switched on and off by nuclear vibrations on a superradiant time scale determined by the collective nuclear frequency, which is of the order of terahertz. Namely, if the incident gamma wave is detuned from the nuclear transition by much larger frequency it passes through the static nuclear array. However, if the nuclei vibrate with the frequency of the gamma ray detuning then parametric resonance can yield energy transfer into the Bragg deflected beam on the superradiant time scale, which can be used for fast control of gamma rays.Comment: 9 pages, 5 figure

Storage and Control of a Single Photon Wave Packet

Quantum optical memory implies the storage of quantum state of light in an atomic ensemble and its retrieval at the later moment of time on demand. It is one of the key elements of both quantum communication and quantum computing. Two types of quantum optical memory techniques have been developed in the last decade. The first one is based on an optimal temporal shaping of the amplitude of a strong coherent control field, forming along with the quantum field a three-level configuration in atomic medium (such as EIT and Raman quantum memories). The second one is based on photon echo mechanism [such as atomic frequency comb (AFC) and gradient echo memory (GEM)]. Each method has its advantages and disadvantages, but in general, an experiment-friendly, reliable, high speed, low loss, broad band quantum storage of a single-photon wave packet with large efficiency and fidelity remains a very challenging task. Here we propose two new quantum optical storage techniques to resolve some of the difficulties and to introduce more controllability over the single-photon processing. The first method is based on phase matching control in Raman configuration (via the modulation in time of the control field's refractive index, propagation direction, and/or carrier frequency chirp). The second method is based on (continues or discrete) spatial frequency chirp of a control field. In order to overcome some general problems inherent to light-atoms interfaces, we propose also a new quantum interface based on γ -ray-nuclear transitions, which looks promising for quantum information processing