Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster: Photonics, laser development and applications, ultrashort laser pulses, quantum effects

Q 30.17: Poster

Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais

A narrowband Photon Pair Source based on Spontaneous Parametric Down-Conversion — •Matthias Bock, Andreas Lenhard, and Christoph Becher — Universität des Saarlandes, FR 7.2 Experimentalphysik, Campus E2.6, 66123 Saarbrücken

Narrowband photon pair sources have become an essential part in quantum networking and quantum repeaters with photons serving as flying qubits. In quantum repeaters one photon will be absorbed by a quantum node (e.g. trapped ions or atoms) while its partner is sent via a fiber communication link. Thus, one of the photons has to fit the atomic transition in center wavelength and linewidth while the other one should be in the low-loss telecom band. At the same time a high heralding efficiency is desirable.
We present such a pair source based on spontaneous parametric down-conversion (SPDC) in a single-resonant optical parametric oscillator (OPO) operating far below oscillation threshold. The OPO consists of a MgO-doped PPLT crystal and is widely tunable from 810nm to 955nm in the signal mode and from 1200nm to 1565nm in the idler mode. We show that the signal could be tuned to an atomic resonance (e.g. Cs or Ca⁺) while the corresponding idler is located at telecom wavelengths. The resonator shapes the spectrum to a comb-like structure with lines separated by 1GHz and a FWHM of 44MHz. With an additional filter we cut out one single line of the OPO-spectrum and measure the spectral and temporal characteristics of the source including the signal-idler cross correlation and the heralding efficiency.