Photon antibunching
= Photon antibunching
{wiki}
<Photon antibunching> means suppression of close pairs compared with pairs at some later delay: $g^{(2)}(0)<g^{(2)}(\tau)$ for some $\tau$. If correlations decay to the independent-count reference, $g^{(2)}(0)<1$ is a sufficient signature. It violates the classical intensity bounds in <photon bunching>. For the specified single-mode number measurement, <second-order optical coherence> also shows that $g^{(2)}(0)<1$ is equivalent to $\operatorname{Var}N<\mu$. This variance criterion concerns that mode or gate; it must not be applied unchanged to arbitrarily long integrated counting intervals.