Thermal photon statistics in spontaneous parametric downconversion

Abstract

We investigate photon statistics in the signal beam generated by frequency nondegenerate parametric downconversion both with and without a seed field along the idler direction. The experiments are performed on the signal generated in beta-barium borate by a traveling-wave pump pulse that is the frequency-tripled output of an amplified Nd:YLF picosecond laser. The high powers obtained allow us to measure the number of photons with a simple detection technique. When both signal and idler fields are initially in their vacuum states, the generated fields are mixtures of equally occupied modes with thermal photon-number statistics.

Statistics of twin-beam states by photon-number resolving detectors up to pump depletion

“…The existence of an evolution of the number of modes of the radiation field is testified by the detected-photon number distributions in the signal arm at different values of the pump mean power. In fact, in continuity with what was expected (and verified [4]) in the undepleted pump approximation, we can assume that the signal photon number distribution is described by the following multimode thermal distribution:…”

“…Many experimental works, performed in very different intensity regimes and with different kinds of detectors, are aimed at characterizing the properties of TWB states, mainly concerning photon-number statistics [4][5][6][7][8][9][10] and correlations [11][12][13][14][15][16]. In fact, TWB states both at single-and at multiphoton levels exhibit strong nonclassical correlations between the two parties in several degrees of freedom (linear position and momentum, frequency, polarization, angular momentum, etc.)…”

Sub-shot-noise photon-number correlation in a mesoscopic twin beam of light

“…The distributions of the detected photons collected by the pin-holes are temporally multimode [16]. In order to demonstrate that we selected twin coherence areas we plot in the Inset of Fig.…”

Experimental Reconstruction of Photon Statistics without Photon Counting

“…The pump, incident orthogonally to the crystal face, had an intensity ∼ 60 GW/cm 2 . In this experimental condition we expect a coherence time of the generated field of ∼ 1 ps, that corresponds to measuring a convolution of 4-5 temporal modes [15]. The photon number distribution is expected to be a multithermal distribution of the form…”