Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 12: Quantum Information III

Q 12.1: Group Report

Tuesday, April 3, 2001, 15:45–16:15, H 3010

Photons generated by vacuum-stimulated Raman scattering — •Axel Kuhn, Markus Hennrich, Thomas Legero, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, D-85748 Garching

Photon sources are key elements in optical quantum information processing. Most emit photons at random times, and triggered emitters were demonstrated only recently. Among these is a Coulomb-blockade based device, a fluorescing molecule, an excited colour centre or a quantum dot. However, their photons are emitted into many modes of the radiation field.

We demonstrate a new scheme, where an atom emits one photon into a single mode of a high-finesse cavity [1]. It is based on adiabatic Raman scattering (STIRAP), with the emission stimulated by the vacuum field of the cavity [2]. The process shows a characteristic dependence on the cavity- and pump detuning, which agrees well with theory. The sub-natural line width of the observed excitation spectrum proves that the system adiabatically follows a dark state, with no excited-state contribution. Photons of well-defined frequency and direction are emitted from the cavity, which opens up new prospects for the entanglement of matter with light, and even a “quantum network” of cavities [3] seems at reach.

[1] M. Hennrich et. al., Phys.Rev.Lett. 85, 4872-4875 (2000)

[2] A. Kuhn et. al., Appl.Phys.B 69, 373-377 (1999)

[3] J.I. Cirac et. al., Phys.Rev.Lett. 78, 3221-3224 (1997)