Quantum memory, as an essential part of a quantum repeater, is the key element for extending quantum communication beyond its current distance limit of around 100 km. In addition to memories, quantum communication tasks require state manipulation and measurement. This is generally accomplished by means of interferometric optical setups, which often suffer from the requirement of phase stabilization. In this thesis we investigate a novel, particularly robust and versatile quantum state transformation approach based on photon-echo type atom-light interaction that allows combining storage with controlled transformation of quantum states. The possibility of modifying a 100% efficient quantum memory protocol to perform this operation is studied and an experimental test-bed based on the traditional stimulated photon echo process is proposed. The method is demonstrated through simulations and experimental studies of nonorthogonal state discrimination, which is of special interest for quantum information processing from the fundamental as well as practical point of view.
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