Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond

The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.Comment: 4 pages, 4 figure

Experimental open air quantum key distribution with a single photon source

We present a full implementation of a quantum key distribution (QKD) system with a single photon source, operating at night in open air. The single photon source at the heart of the functional and reliable setup relies on the pulsed excitation of a single nitrogen-vacancy color center in diamond nanocrystal. We tested the effect of attenuation on the polarized encoded photons for inferring longer distance performance of our system. For strong attenuation, the use of pure single photon states gives measurable advantage over systems relying on weak attenuated laser pulses. The results are in good agreement with theoretical models developed to assess QKD security

Vergleich von zerebraler Nahinfrarotspektroskopie und einer Kombination von Weißlichtspektrometrie und Laser-Doppler-Spektroskopie bei postoperativen Säuglingen auf der Intensivstation

Nichtinvasive Messmethoden der zerebralen Sauerstoffgewebesättigung (cSO2), wie die Nahinfrarotspektroskopie oder die „Oxygen to see“-Methode (O2C) finden in der Behandlung von Kindern mit angeborenen Herzfehlern immer mehr Beachtung. Durch ein deutlich verbessertes Therapieregime erreichen über 85% der Kinder mit angeborenem Herzfehler inzwischen das Erwachsenenalter. Die vorliegende Arbeit soll zwei Messmethoden zur zerebralen Sauerstoffgewebesättigung evaluieren und vergleichen

Trained MT Metrics Learn to Cope with Machine-translated References

Neural metrics trained on human evaluations of MT tend to correlate well with human judgments, but their behavior is not fully understood. In this paper, we perform a controlled experiment and compare a baseline metric that has not been trained on human evaluations (Prism) to a trained version of the same metric (Prism+FT). Surprisingly, we find that Prism+FT becomes more robust to machine-translated references, which are a notorious problem in MT evaluation. This suggests that the effects of metric training go beyond the intended effect of improving overall correlation with human judgments

Trained MT Metrics Learn to Cope with Machine-translated References

Neural metrics trained on human evaluations of MT tend to correlate well with human judgments, but their behavior is not fully understood. In this paper, we perform a controlled experiment and compare a baseline metric that has not been trained on human evaluations (Prism) to a trained version of the same metric (Prism+FT). Surprisingly, we find that Prism+FT becomes more robust to machine-translated references, which are a notorious problem in MT evaluation. This suggests that the effects of metric training go beyond the intended effect of improving overall correlation with human judgments.Comment: WMT 202