We report on the measurement of the noise statistics of spontaneous parametric fluorescence in a fiber optical parametric amplifier with single-mode, single-photon resolution. The results agree with quantum theoretical predictions.
We experimentally demonstrate an improvement of 0.7±0.1 dB in the noise figure in a low noise fiber-optical parametric amplifier (FOPA) with the injection of correlated quantum fields generated from spontaneous four-wave mixing in fibers. The noise performance of the amplifier is characterized with homodyne detectors. The experimental result shows that the noise levels in the two output ports (signal and idler) of the amplifier are both 1.0±0.1 dB lower than a regular FOPA with vacuum at the unused input port. In addition, we demonstrate the scheme can be used as a quantum information tap with a combined information transfer efficiency (signal and tap) as Tsig+Ttap=1.47±0.2, which is larger than the classical limit of 1. This low noise FOPA can be applied to the low noise amplification in the measurement of weak signals.
The recently developed method of optical homodyne tomography (OHT) allows one to obtain the photon statistics of a single mode with single-photon resolution. Recently, we used OHT to prove the Bose Einstein distribution (BED) character of parametric fluorescence. In general, in an OHT setup, a weak signal beam is mixed on a 50/50 beamsplitter with a strong local oscillator beam of the same polarization and spatio-temporal mode. In this paper, we apply OHT to show, we believe for the first time, that ASE noise of a single mode in an EDFA is Bose-Einstein distributed.