page_title: Photon statistics
section_title: Sub-Poissonian Light
hierarchical_section_title: Photon statistics / Sub-Poissonian Light
caption_attribution_description: English: Schematic of the homodyne intensity correlation scheme. SI, signal field, LO, local oscillator, BS, beam splitter, SL, superimposed light, C, correlator. The black boxes are the detectors that send electrical signals to the correlator where the intensity correlation of the superimposed field is measured.
context_page_description: Photon statistics is the theoretical and experimental study of the statistical distributions produced in photon counting experiments, which use Photodetectors to analyze the intrinsic statistical nature of photons in a light source. In these experiments, light incident on the photodetector generates photoelectrons and a counter registers electrical pulses generating a statistical distribution of photon counts. Low intensity disparate light sources can be differentiated by the corresponding statistical distributions produced in the detection process.
  Three regimes of statistical distributions can be obtained depending on the properties of the light source: Poissonian, super-Poissonian, and sub-Poissonian. The regimes are defined by the relationship between the variance and average number of photon counts for the corresponding distribution. Both Poissonian and super-Poissonian light can be described by a semi-classical theory in which the light source is modeled as an electromagnetic wave and the atom is modeled according to quantum mechanics.
context_section_description: Light that is governed by sub-Poisson statistics cannot be described by classical electromagnetic theory and is defined by  . The advent of ultrafast photodetectors has made it possible to measure the sub-Poissonian nature of light. An example of light exhibiting sub-Poissonian statistics is squeezed light. Recently researchers have shown that sub-Poissonian light can be induced in a quantum dot exhibiting resonance fluorescence. A technique used to measure the sub-Poissonian structure of light is a homodyne intensity correlation scheme. In this scheme a local oscillator and signal field are superimposed via a beam splitter. The superimposed light is then split by another beam splitter and each signal is recorded by individual photodetectors connected to correlator from which the intensity correlation can be measured. Evidence of the sub-Poissonian nature of light is shown by obtaining a negative intensity correlation as was shown in.
caption: Schematic of the homodyne intensity correlation scheme described in [6]. SI, signal field, LO, local oscillator, BS, beam splitter, SL, superimposed light, C, correlator. The photodetectors (black elements) send electrical signals to the correlator where the intensity correlation is measured.
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