We use the third- and fourth-order autocorrelation functions g(3)(τ1,τ2) and g(4)(τ1,τ2,τ3) to detect the nonclassical character of the light transmitted through a photonic-crystal nanocavity containing a strongly coupled quantum dot probed with a train of coherent light pulses. We contrast the value of g(3)(0,0) with the conventionally used g(2)(0) and demonstrate that, in addition to being necessary for detecting two-photon states emitted by a low-intensity source, g(3) provides a more clear indication of the nonclassical character of a light source. We also present preliminary data that demonstrates bunching in the fourth-order autocorrelation function g(4)(τ1,τ2,τ3) as the first step toward detecting three-photon states.
- photonic crystal nanocavity
- quantum dot