Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 57: Quanteneffekte (QED / Lichtstreuung)

Q 57.2: Talk

Friday, March 14, 2008, 11:15–11:30, 2D

From a single-photon emitter to a single ion laser — •Helena G. Barros^1,2, François Dubin¹, Carlos Russo^1,2, Andreas Stute^1,2, Piet O. Schmidt¹, and Rainer Blatt^1,2 — ¹Institut für Experimentalphysik, Universiät Innsbruck, Technikerstr. 25, A-6020 Innsbruck — ²Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Otto-Hittmair-Platz 1, A-6020 Innsbruck

A single atom interacting with a single mode of a cavity is the building block of a laser from a fundamental point of view. In this work, we study a single ⁴⁰Ca⁺ ion coupled to a high finesse optical resonator. In particular, we evaluate the statistical properties of emitted cavity photons for different regimes of operation.

In the experiment, a drive laser together with an optical cavity excites an off-resonant Raman transition that connects the S_1/2 and D_3/2 levels of the ⁴⁰Ca⁺ ion. Population gets transferred from S_1/2 to D_3/2 while emitting a photon into the cavity. The excitation cycle is closed by a recycling laser that brings the atomic population back to the initial state S_1/2 via resonant excitation of the P_1/2 state. The photons leave the cavity at a rate of 54 kHz and are sent to a Hanbury-Brown & Twiss setup, where photon-photon correlations are measured. For weak recycling laser intensity, the system is operating as a single-photon source. In this regime, we can tune the statistics of the photon arrival times from sub-Poissonian to super-Poissonian behaviour. For faster recycling rates, we observe a single-atom laser at threshold. Different criteria for lasing in such a system are discussed.