**Relaxing symmetry in CRIB: Combining quantum state storage with data transformation**

Relaxing symmetry in CRIB: Combining quantum state storage with data
transformation
A. Delfan1, C. La Mela1, M. S. Underwood1, K.-P. Marzlin1, S. Moiseev1,2, and W. Tittel1
1Institute for Quantum Information Science, University of Calgary, Canada
2Kazan Physical-Technical Institute, Russian Academy of Science, Russia
Quantum repeater [1], based on sources of entangled photons, quantum memory, and
single and two qubit gates plus measurements, promise overcoming the distance barrier
of quantum communication protocols. We investigate extensions of a recent quantum
memory protocol based on controlled, reversible, inhomogeneous broadening (CRIB) [2-
5] for combining quantum state storage with transformation of the absorbed quantum
data. More precisely, we relax the symmetry requirement between inhomogeneous
broadening during quantum state absorption and recall, as required for perfectly timereversed
quantum dynamics. We will discuss possibilities for single qubit rotations based
on sequential rephrasing [3], and propose an experiment based on stimulated photon
echoes [4], which serves as a test-bed for the more efficient, CRIB based realization.
Other types of quantum (or classical) data transformation arise from asymmetry in the
rate of de-and rephasing, leading to data compression or decompression [5].
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043602 (2006).
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020302(R) (2006).
[6] see contribution by M.S.Underwood et al.
[7] see contribution by A. Delfan et al.
[8] see contribution by S. Moiseev et al.