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キーワード:
PARAMETRIC DOWN-CONVERSION; HIGH-ACCURACY; PHOTON; CALIBRATION;
METROLOGY; TIMEComputer Science; Physics; Quantum optics; absolute calibration; twin-beam squeezed vacuum;
要旨:
We realize and test in experiment a method recently proposed for measuring absolute quantum efficiency of analog photodetectors. Similar to the traditional (Klyshko) method of absolute calibration, the new one is based on the direct detection of two-mode squeezed vacuum at the output of a traveling wave OPA. However, in the new method, one measures the difference-photocurrent variance rather than the correlation function of photocurrents (number of coincidences), which makes the technique applicable for high-gain OPA. In this work we test the new method versus the traditional one for the case of photon-counting detectors where both techniques are valid.
