Maria Tengner

Bright, single-spatial-mode source of frequency non-degenerate, polarization-entangled photon pairs using periodically poled KTP

We use two perpendicular crystals of periodically-poled KTP to directly generate polarization-entangled photon pairs, the majority of which are emitted into a single Gaussian spatial mode. The signal and idler photons have wavelengths of 810 nm and 1550 nm, respectively, and the photon-pair generation rate is 1.2x107 sec-1 for a pump power of 62 mW. The apparatus is compact, flexible, and easily to use.

Optimal focusing for maximal collection of entangled narrow-band photon pairs into single-mode fibers

We present a theoretical and experimental investigation of the emission characteristics and the flux of photon pairs generated by spontaneous parametric downconversion in quasi-phase matched bulk crystals for the use in quantum communication sources. We show that, by careful design, one can attain well defined modes close to the fundamental mode of optical fibers and obtain high coupling efficiencies also for bulk crystals, these being more easily aligned than crystal waveguides. We distinguish between singles coupling,

Narrowband polarization-entangled photon pairs distributed over a WDM link for qubit networks

{\ensuremath{\gamma}}_{\mathrm{s}}

Theory and experiment of entanglement in a quasi-phase-matched two-crystal source

and

Single crystal source of polarization entangled photons at non-degenerate wavelengths

{\ensuremath{\gamma}}_{\mathrm{i}}

Robust decoy-state quantum key distribution with heralded single photon source

, conditional coincidence,

Quantum Communication in Optical Networks: an Overview and Selected Recent Results

{\ensuremath{\mu}}_{\mathrm{i}\ensuremath{\mid}\mathrm{s}}

Single-photon correlations for secure communication

, and pair coupling,

A source of entangled photon-pairs : Optimizing emission in two quasi-phasematched crystals

{\ensuremath{\gamma}}_{\mathrm{c}}

Bright source of polarization-entangled photons using periodically poled potassium titanyl phosphate (KTP)

, and show how each of these parameters can be maximized by varying the focusing of the pump mode and the fiber-matched modes using standard optical elements. Specifically we analyze a periodically poled KTP-crystal pumped by a