antibunchingVerteilung

Antibunching refers to a phenomenon observed in quantum optics where photons emitted from a source are statistically less likely to be detected simultaneously than would be expected from a random (Poissonian) distribution. In simpler terms, a single photon source is more likely to emit one photon at a time, rather than two or more at the same instant. This correlation, or rather the absence of correlation at short time delays, is a hallmark of single-photon emitters.

The statistical description of photon emission is often characterized by the second-order correlation function, denoted as g^(2)(τ), where τ is the time delay between detecting two photons. For a classical light source, such as a thermal lamp, g^(2)(0) is greater than 1, indicating bunching, meaning photons are more likely to arrive in bunches. For coherent light, like that from a laser, g^(2)(0) is equal to 1, representing a Poissonian distribution. However, for an ideal single-photon source, g^(2)(0) is 0, signifying perfect antibunching. This means that if a photon is detected at time t, it is impossible to detect another photon from the same source at time t.

Observing antibunching is crucial evidence for the quantum nature of light and is a key indicator that a source is behaving as a true single-photon emitter. Such sources are essential for various quantum technologies, including quantum cryptography, quantum computing, and quantum metrology, where precise control over individual photons is required. Experiments demonstrating antibunching typically involve a photodetector and a beam splitter, where the arrival times of photons at the two output ports are measured and correlated.