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Coherent control in a decoherence-free subspace of a collective multi-level system

M. Kiffner·J. Evers·C. H. Keitel
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Abstract

Decoherence-free subspaces (DFS) in systems of dipole-dipole interacting multi-level atoms are investigated theoretically. It is shown that the collective state space of two dipole-dipole interacting four-level atoms contains a four-dimensional DFS. We describe a method that allows to populate the antisymmetric states of the DFS by means of a laser field, without the need of a field gradient between the two atoms. We identify these antisymmetric states as long-lived entangled states. Further, we show that any single-qubit operation between two states of the DFS can be induced by means of a microwave field. Typical operation times of these qubit rotations can be significantly shorter than for a nuclear spin system.

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M. Kiffner, J. Evers, C. H. Keitel. 2006-11-08. Coherent control in a decoherence-free subspace of a collective multi-level system. https://doi.org/10.1103/physreva.75.032313

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