Arrangör/Organiser: Fysikum/Stockholms Universitet
Webbadress/Webpage: https://stockholmuniversity.zoom.us/s/239996391
Kontakt/Contact: Alban Seguinard
Ingen föranmälan krävs/No registration required

 

Abstract:
A single photons down-conversion source which produces polarized entangled pair photons at 780 nm and 1550 nm was developed and characterized in order to be used with for
quantum optics and quantum communication experiments. These two wavelengths are extremely interesting for the laboratory, the 780 nm corresponds to D2 (52S1/2→52P3/2)
optical transition for rubidium-87 atom and possible use for quantum memories and the 1550 nm correspond the telecom wavelength with low loss for long distance optical
communication. We have designed the source to generated polarization entanglement. The entangled photons were produced by pumping a 15 mm long periodically poled
Potassium Titanyl Phosphate crystal (ppKTP) with a 518.9 nm stabilized laser diode inside a Sagnac interferometric configuration. The source produces two-qubit maximally entangled state with very high fidelity of 96.95%. We have tested the violation of Bell inequality and we have obtained a violation of 2.765 > 2.

In addition, I also developed a characterization setup for testing single photon detectors based on nanowires superconductors (SSPD) to measure and calibrate their quantum efficiency, dark counts and time jitter.