13. SM photon anti-bunching setup
The fluorescence from a presumably single molecule is split by a 1:1 beam splitter, and the two signals are sent into separate detectors. The setup delivers a histogram of the difference between the arrival times of photons at both detectors. In case of a single emitter, the probability to emit more than one photon after excitation is zero. Hence the probability for a difference in arrival time shorter than the excited-state lifetime is very small.
ps laser system, confocal microscope, dual-channel detection part.
The setup is used to estimate the probability for detecting multiple photons. This probability approaches zero upon decreasing the detection time window to times shorter than the excited state lifetime. In other words, the experiment verifies whether the emitters are entangled, or there is only a single emitter present.