Quantum computing based on one-photon polarisation states of light pulses propagating in a doped resonance medium

The propagation of one-photon light pulses in optical media doped with rare-earth atoms is considered under conditions close to the atomic optical resonance. The four-beam polarisation interaction M-scheme with two probe pulses and two pump pulses is analysed. The regimes of induced cross-interaction between probe optical pulses are studied and the conditions are found for controlling efficiently their group velocities in the medium, which is determined by the tunings of the atomic optical resonance. An algorithm is proposed for quantum information processing by coding and controlling the time delays of one-photon light pulses in this system.