Freiburg 2019 – wissenschaftliches Programm
FM 74.2: Talk
Donnerstag, 26. September 2019, 14:30–14:45, 1009
ppKTP Entangled Photon Source Study and a New Scheme — •Adrià Sansa Perna1 and Fabian Steinlechner2 — 1Friedrich-Schiller University Jena, Abbe School of Photonics, Albert-Einstein-Str. 5, 07745 Jena, Germany. — 2Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 07745 Jena, Germany.
An ultra-bright ppKTP crossed-crystal entangled photon source ready for use in quantum cryptography is designed and studied, leading to the possibility of a new entangled photon source scheme. First, a theoretical study of the efficiency parameters of the source is modelled taking into account deviations in the profile of the entangled photons. The source is thereafter build consistently with this results. It is shown to have a high brightness of 1.78 milion pairs/s/mW a brightness of the order of more complex interferometric sources, and a good quantum state fidelity of 95.6%. Its high brightness allows for the further study of the beam profile of the SPDC generated at different temperatures. This study of the beam profile allows the characterization of the SPDC emission in temperatures below phase-matching, and SPDC is seen to form a ring profile. The profile observed is modelled theoretically and the total amount of photons generated at different phase-matching conditions is calculated. This reveals the possibility of a new kind of source capable of delivering simultaneously entangled photons to various pairs of users. This new scheme for a source would allow to increase the number of users connected in a quantum network, one of the key aspects missing in developing quantum cryptographic technologies.