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]. [1] H. Briegel, W. Dür, I. Cirac, P. Zoller, Phys. Rev. Lett. 81, 5932(1998) [2] S. A. Moiseev and S. Kröll, Phys Rev Lett. 87, 173601(2001), [3] M. Nilsson and S. Kröll, Opt. Commun. 247, 292 (2005), [4]} A. L. Alexander, J. J. Longdell, N. B. Manson, and M. J. Sellars Phys. Rev. Lett. 96, 043602 (2006). [5] B. Kraus, W. Tittel, N. Gisin, M. Nilsson, S. Kroll, and J. I. Cirac, Phys. Rev. A. 73, 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.