Strong interaction between light and a single trapped atom without the need for a cavity

Abstract

An experiment that demonstrates efficient absorption of light by a single atom residing in free space should be helpful for designing interfaces for the transfer of quantum information from ‘flying’ qubits to stationary quantum systems, without the need for optical cavities. Many quantum information processing protocols require efficient transfer of quantum information from a flying photon to a stationary quantum system1,2,3. To transfer information, a photon must first be absorbed by the quantum system. This can be achieved, with a probability close to unity, by an atom residing in a high-finesse cavity1. However, it is unclear whether a photon can be absorbed effectively by an atom in a free space. Here, we report on an observation of substantial extinction of a light beam by a single 87Rb atom through focusing light to a small spot with a single lens. The measured extinction values can be directly compared to the predictions of existing free-space photon–atom coupling models4,5,6. Our result should open a new perspective on processing quantum information carried by light using atoms, in particular for experiments that require strong absorption of single photons by an atom in free space.

Cite this article

Tey, M., Chen, Z., Aljunid, S. et al. Strong interaction between light and a single trapped atom without the need for a cavity. Nature Phys 4, 924–927 (2008). https://doi.org/10.1038/nphys1096

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