arXiv subjects

Katsuyuki Kasai

Publications and source records attributed to Katsuyuki Kasai.

4 recordsLinked to original sources

arXiv2005

Conditional transfer of quantum correlation in the intensity of twin beams

A conditional protocol of transferring quantum-correlation in continuous variable regime was experimentally demonstrated. The quantum-correlation in two pairs of twin beams, each characterized by intensity-difference squeezing of 7.0 dB, was transferred to two initially independent idler beams. The quantum-correlation transfer resulted in intensity-difference squeezing of 4.0 dB between two idler beams. The dependence of preparation probability and transfer fidellity on the selection bandwidth was also studied.

quant-ph↗

arXiv2004

Generation of twin beams from an optical parametric oscillator pumped by a frequency-doubled diode laser

Quantum-correlated twin beams were generated from a triply resonant optical parametric oscillator with an a-cut KTP crystal pumped by a frequency-doubled diode laser. A total output of 5.1 mW was obtained in the classical-to-nonclassical-light conversion system driven by a 50-mW diode laser at 1080 nm. Quantum noise reduction of 4.3 dB (63%) in the intensity difference between the twin beams was successfully observed at the detection frequency of 3 MHz.

quant-ph↗

arXiv2004

Single-beam noise characteristics of quantum correlated twin beams

We investigated the intensity noise spectra of the single beam of a pump-enhanced continuous-wave (cw) optical parametric oscillator (OPO), which was used to generate quantum correlated twin beams, as a function of the pump power. With a triply (pump-, signal-, and idler-) resonant cavity, the oscillation threshold of our OPO was about 8.5+/-1.3 mW and the measured slope conversion efficiency was 0.72+/-0.02. A twin beams with power of 240 mW were generated at pump power of 350 mW. The relaxation oscillation frequencies, which depend on the pump power, were observed when the pump power of OPO was from 12.5 mW to 28 mW. The experimental results confirm the predicted increase in OPO relaxation frequency with pump power. Squeezing of the single beam intensity was for the first time inferred experimentally by exploiting nature of quantum noise dependent on loss.

quant-ph↗

arXiv2004

Quantum channel using photon number correlated twin beams

We report quantum communications channel using photon number correlated twin beams. The twin beams are generated from a nondegenerate optical parametric oscillator, and the photon number difference is used to encode the signal. The bit error rate of our system will be 0.067 by using the twin beams comparing with 0.217 by using the coherent state as the signal carrier.

quant-ph↗