Separate particle detectors measure the quantum states of each particle and send the resulting signal to a coincidence counter.

This limits coincidence counters to improving the signal to noise ratio to the extent that the quantum behavior can be studied, without removing the noise completely.

The entangled photons, as filtered with the help of the coincidence counter, are simulated in Fig. 5 to give a visual impression of the evidence available from the experiment.

With a coincidence counter, the dancing interference pattern would be stronger at times of increased intensity [common to both beams], and that pattern would be stronger than the background noise.)

He added: 'The two systems, an Alpha Drum Monitor and a Neutron Coincidence Counter, are results of development and design expertise from both Risley and Sellafield built up over recent years.

By using a coincidence counter, the experimenters were able to isolate the entangled signal from photo-noise, recording only events where both signal and idler photons were detected (after compensating for the 8 ns delay).

The Polygraphic coincidence counter (Frequency analysis) (German:Saegebock, English:Sawbuck) was a machine for recording the frequency of polygraphs occurring in a message, or for recording the frequency of polygraphic coincidences between messages.

In a two detector system, a coincidence counter alleviates this problem by only recording detection signals that strike both detectors simultaneously (or more accurately, recording only signals that arrive at both detectors and correlate to the same emission time).