Spectrally-resolved higher-order photon statistics of spontaneous parametric down-conversion

Time-correlated single photon counting (TCSPC) data is obtained using a
Becker & Hickl DPC-230 correlation board in order to study the
photon statstics of the incident light beam as functions of different
parameters. Here specifically, the photon statistics of spontaneous
parametric down-conversion (SPDC) exhibit dependencies on wavelength, pump
power, and coincidence time. Notably, the average photon numbers were
found to asymmetrically increase with increasing pump power around the
degenerate wavelength of emission. By the coupling of the detection scheme
to a spectrometer, studying different bandwidths within the emission
revealed that shorter wavelengths increased nonlinearly with pump power,
while longer wavelengths showed more linear behavior, indicating a
wavelength-dependent efficiency in the generation of the SPDC. We employ
the use of a four-detector Hanbury Brown and Twiss Interferometer to study
the photon statistics of the signal beam, where the idler serves as the
herald. The measured statistics were found to be best described by a
Negative Binomial Distribution, which is a characteristic of thermal light
sources. The detection and characterization of complex light sources has
wide ranging applications in the fields of quantum metrology, quantum
communications, and quantum computing, more specifically, a system that is
sensitive to wavelength and photon number distribution.