Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 35: Poster 2
Q 35.78: Poster
Wednesday, March 14, 2012, 16:30–19:00, Poster.I+II
Pulsed Sagnac Source of Polarisation-Entangled Photon Pairs — Ana Predojević1, •Stephanie Grabher1, and Gregor Weihs1,2 — 1Institut für Experimentalphysik, Universität Innsbruck, Austria — 2Institute for Quantum Computing, University of Waterloo, Canada
Entangled photon pairs are used in several important quantum information applications including quantum networks and quantum computing. Moreover, they are a crucial component for multi-photon experiments like entanglement swapping. In addition, photonic quantum information experiments demand bright and highly entangled photon pair sources.
We demonstrate a picosecond-pulsed laser pumped system for the generation of entangled photon pairs. The down-conversion source is realized in a Sagnac-interferometer based geometry. The characteristics of this type of polarisation-entangled photon source are wavelength tunability and intrinsic phase stability. The combination of periodic poling and collinear excitation allows the use of long crystals. We characterized the Sagnac source by measuring the entanglement visibility and performing quantum state tomography. The measurements yielded visibilities of 99.88(3)% and 98.70(9)% in the rectilinear and diagonal linear bases, respectively, a tangle of 96.50(83)% and a fidelity of 98.20(70)% with the | Ψ+ ⟩ -Bell state. Furthermore, we measured the influence of the Gouy phase shift onto the phase of the output state.
This research was funded in part by the European Research Council (ERC) and the Austrian Science Fund (FWF).