Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 17: Quantum Repeater and Quantum Communication
Q 17.7: Vortrag
Dienstag, 7. März 2017, 12:30–12:45, P 3
Quantum Frequency Down-Conversion of Ca+–Resonant Polarization–Entangled Photons to the Telecom O-Band — •Matthias Bock, Stephan Kucera, Jan Arenskötter, Benjamin Kambs, Sebastian Rühle, Andreas Lenhard, Jürgen Eschner, and Christoph Becher — Universität des Saarlandes, Fakultät NT, FR Physik, Campus E2.6, 66123 Saarbrücken
A typical quantum repeater scenario comprises stationary atomic quantum memories and photonic fiber links to distribute information between these memories. In order to link the photons to the internal states of the atomic system, it is useful to encode the information in their polarization degree of freedom. A drawback is that the typical transition wavelengths in the red or NIR spectral region suffer high losses in optical fibers. Thus, an interface between these transition wavelengths and the low–loss telecom regime, which moreover preserves the polarization state of the photons, is required.
We present the implementation of a polarization–preserving frequency converter connecting 854 nm, the wavelength of the 42P3/2↔ 32D5/2 transition of a trapped Ca+–ion, to the telecom O-band at 1312 nm. It is achieved via difference frequency generation in a nonlinear waveguide, which is arranged in a Sagnac configuration to ensure polarization independence. With high external conversion efficiency of 32.5% and low unconditional noise of 50 cts/s we are able to convert photons from a polarization–entangled pair at 854 nm generated by a cavity–enhanced pair source (linewidth: 10MHz) to the telecom O-band, and we show the preservation of the entanglement with high fidelity.