Generating non-classical light using Rydberg interactions
Mercredi 25 avril 2012
à 11h en salle C. Brot
We study, both theoretically and experimentally, the possibility to use a cloud of Rydberg atoms as a strongly non-linear optical medium, which should enable strong photon-photon interactions and allow one to deterministically create non-classical states of light.
Atomic ensembles play a prominent role in quantum optics. For instance, the quantum state of a light beam can be stored in an ensemble of cold atoms as a polarisation wave involving two long-lived atomic states. If one of these atomic states is a Rydberg state, this polariton will evolve due to long-range atomic interactions. As a result, a coherent pulse of light stored in the atomic medium should turn into a non-classical polaritonic state which could be retrieved as a pulse of non-classical light. We have theoretically shown that the Rydberg gas should act as “quantum scissors” on the stored quantum state, and the retrieved optical pulse should become a coherent superposition of zero and one photons presenting a non-classical, negative Wigner function. We have also found realistic experimental parameters to retrieve this pulse with a high efficiency in a well-defined spatial and temporal mode, which should make the non-classical properties of the state observable in a homodyne measurement. Currently, as a first step in this direction, we are experimentally investigating the non-linear optical dispersion of a Rydberg cloud trapped inside a low-finesse optical cavity.
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