Hamburg 2009 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Quanteninformation: Photonen I
Q 18.2: Talk
Tuesday, March 3, 2009, 10:45–11:00, VMP 6 HS-D
Heralded Single Photons from Cavity-Enhanced Parametric Down-Conversion — •Lars Koch, Matthias Scholz, and Oliver Benson — Humboldt-Universität zu Berlin, Institut für Physik, AG Nano Optik, Hausvogteiplatz 5-7, 10117 Berlin
A promising scheme for quantum networks uses single photons and atomic ensembles to interconvert between flying and stationary photonic
qubits. Thus, single-photon sources with spectral bandwidths of only a few MHz are required that efficiently couple to atomic resonances.
We demonstrate the generation of narrow-band single photons with a spectral width of only 3 MHz by cavity-enhanced parametric down-conversion in
PPKTP. A compensating KTP crystal allows triple-resonance of pump, signal, and idler fields. Locking the cavity via the Hänsch-Couillaud method, we
achieve long-term stability and an ultra-high brightness of 14000 biphotons/s per mW pump power and MHz signal bandwidth in the TEM00
mode on the cesium D1 line (894.3 nm). Moreover, we give proof of the single-photon character by detection of heralding idler photons that trigger
a Hanbury-Brown and Twiss setup for the signal field. Compared to a Poissonian source, the multi-photon emission probability is reduced by a factor
of 100.