Frankfurt 2006 – scientific programme

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Q: Quantenoptik und Photonik

Q 58: Quantenkommunikation

Q 58.2: Talk

Thursday, March 16, 2006, 11:25–11:40, HVI

Quantum Memory and Two-Mode-Squeezing in Atomic Ensembles — •Christine Muschik, Klemens Hammerer, and J. Ignacio Cirac — Max-Planck-Institut für Quantenoptik, Hans Kopfermann-Strasse, D-85748 Garching, Germany

We propose two protocols for atomic ensembles interacting with light. The atomic ensemble is thereby placed in an external magnetic field and provides a fully passive beam-splitter-like or a purely active two-mode-squeezing-like interaction depending on the orientation of the external field. The passive version of the proposed experiment can be used as a quantum memory. A coherent pulse of light or a light-qubit can be written onto the spin state of the atoms and subsequently be read out. Remarkably the fidelity of the state transfer approaches unity exponentially in the coupling strength. The active version of the setup creates an EPR state between atoms and light respectively. The produced interspecies correlations produced in the scheme can be used to perform quantum teleportation and unconditional squeezing on the collective spin of the atomic sample. Spin squeezing which grows exponentially in the coupling can be achieved. Both protocols are shown to be robust against the dominant sources of noise.