[show abstract][hide abstract] ABSTRACT: We present an experimentally feasible protocol for the complete storage and retrieval of arbitrary light states in an atomic quantum memory using the well-established Faraday interaction between light and matter. Our protocol relies on multiple passages of a single light pulse through the atomic ensemble without the impractical requirement of kilometer long delay lines between the passages. Furthermore, we introduce a time dependent interaction strength which enables storage and retrieval of states with arbitrary pulse shapes. The fidelity approaches unity exponentially without squeezed or entangled initial states, as illustrated by explicit calculations for a photonic qubit. Comment: 4 pages, 3 figures For his new version, the original paper has substantially rewritten to make it clearer including completely new introduction and conclusions and a rearrangement of the middle part. A minor mistake in the numerical results has been found and corrected, which resulted in higher values for the fidelities
[show abstract][hide abstract] ABSTRACT: We propose an efficient method for mapping and storage of a quantum state of propagating light in atoms. The quantum state of the light pulse is stored in two sublevels of the ground state of a macroscopic atomic ensemble by activating a synchronized Raman coupling between the light and atoms. We discuss applications of the proposal in quantum information processing and in atomic clocks operating beyond quantum limits of accuracy. The possibility of transferring the atomic state back on light via teleportation is also discussed. Comment: submittted to PRL
[show abstract][hide abstract] ABSTRACT: Recent results and future perspectives in the field of interaction of cold atomic spins with non-classical light are reviewed. We describe how such light can be used for passive probing of the collective atomic spin and for generation of the non-classical correlations between the individual atomic spins.
[show abstract][hide abstract] ABSTRACT: We explore the fundamental noise of the atomic spin measurement performed via polarization analysis of the probe light. The noise is shown to consist of the quantum noise of the probe and the quantum noise of atomic spins. In the experiment with cold atoms in a magneto-optical trap we demonstrate the reduction of the former by 2.5 dB below the standard quantum limit. For the latter we reach the quantum limit set by fluctuations of uncorrelated individual atomic spins. We outline the way to overcome this limit using a recent theoretical proposal on spin squeezing.
Physical Review Letters - PHYS REV LETT. 01/1998; 80(16):3487-3490.