Patent ID: 7220954

Claim:
Apparatus, comprising: apparatus for confining an optically thick atomic cloud that supports a plurality of distinct quantum state transitions and which is configured in a first atomic state; laser apparatus for outputting a write pulse tuned to a transition between the first quantum state and a second quantum state of the atomic cloud, and for outputting a read pulse tuned to a transition between a third quantum state and a fourth quantum state of the atomic cloud; optical apparatus for separately coupling the write and read pulse into two regions of the atomic cloud, wherein, in response to the write pulse, a first photon having a distinct spatial mode is scattered on a transition between the second quantum state and the third quantum state, and wherein, in response to the read pulse, a second photon having a distinct spatial mode is scattered on a transition between the fourth quantum state and the first quantum state; a beam combiner for respectively mapping the distinct spatial modes associated with the first and second photons into first and second polarization encoded photons, respectively, having a single spatial mode with polarization encoding of the laser apparatus; and apparatus for altering the polarization of the first and second polarization encoded photons to respectively alter the quantum state of the atomic cloud and inscribe a quantum bit of information upon the cloud, and read out the quantum bit of information from the cloud.