  We study quantum compression and decompression of light pulses that carry
quantum information using a photon-echo quantum memory technique with
controllable inhomogeneous broadening of an isolated atomic absorption line. We
investigate media with differently broadened absorption profiles, transverse
and longitudinal, finding that the recall efficiency can be as large as unity
and that the quantum information encoded into the photonic qubits can remain
unperturbed. Our results provide new insight into reversible light-atom
interaction, and are interesting in view of future quantum communication
networks, where pulse compression and decompression may play an important role
to increase the qubit rate, or to map quantum information from photonic
carriers with large optical bandwidth into atomic memories with smaller
bandwidth.
