Letter abstract


Nature Physics 4, 924 - 927 (2008)
Published online: 12 October 2008 | doi:10.1038/nphys1096

Subject Categories: Atomic and molecular physics | Optical physics | Quantum physics

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

Meng Khoon Tey1, Zilong Chen2, Syed Abdullah Aljunid1, Brenda Chng1, Florian Huber3, Gleb Maslennikov1 & Christian Kurtsiefer1

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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.

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  1. Center for Quantum Technologies and Department of Physics, National University of Singapore, 3 Science Drive 2, 117543, Singapore
  2. Institute of Materials Research and Engineering, 3 Research Link, 117602, Singapore
  3. Department of Physics, Technical University of Munich, James Franck Street, 85748 Garching, Germany

Correspondence to: Christian Kurtsiefer1 e-mail: christian.kurtsiefer@gmail.com