Comparative Test of Two Methods of Quantum Efficiency Absolute Measurement Based on Squeezed Vacuum Direct Detection

TL;DR

This paper experimentally compares a new method based on squeezed vacuum difference-photocurrent variance with the traditional Klyshko method for absolute quantum efficiency measurement, demonstrating applicability to high-gain OPAs.

Contribution

The study introduces and experimentally tests a novel quantum efficiency measurement technique using squeezed vacuum difference-photocurrent variance, extending calibration capabilities to high-gain OPAs.

Findings

The new method agrees with the traditional method for photon-counting detectors.

It is applicable to high-gain optical parametric amplifiers.

The technique offers a viable alternative for absolute quantum efficiency calibration.

Abstract

We realize and test in experiment a method recently proposed for measuring absolute quantum efficiency of analog photodetectors. Similarly 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.