Storing and processing coherent optical information with ultra-slow light in Bose-Einstein
condensates (BECs)

We explore coherent information transfer between ultra-slow and stopped laser light pulses [1]
and atomic BECs. In [1], pulses of a probe laser were stopped, stored, and later revived by
switching off and on a coupling laser. We show that this switching process can occur coherently
on time scales much faster than the adiabatic time scale for electromagnetically induced
transparency [2]. When this is done in a BEC, the light pulses create spatial features in the
atomic fields and we find the ensuing two-component dynamics gives rise to interference
fringes and solitons. Switching the coupling field back on writes the dynamics onto probe pulses,
allowing the condensate to process the optical information. Extensions to quantum information are

[1] C. Liu, Z. Dutton, C.H. Behroozi, and L.V. Hau, Nature 409, 490 (2001);
D.F. Phillips, et al., Phys. Rev. Lett. 86, 783 (2001).

[2] S.E. Harris, Physics Today 50, 36 (1997).