# I Spatially Resolved Hong Ou Mandel - "Coalescing" Photons

1. Apr 28, 2016

### Swamp Thing

I'm reading this article https://www.osapublishing.org/ol/abstract.cfm?uri=ol-40-7-1540. It is a Hong-Ou-Mandel interferometer in which they can record exactly where each photon of a pair ends up, with a resolution of maybe a hundredth of the output port areas. So you see either two dots in the port A region or two dots in the port B region, but never one dot in port A and one dot in port B. The authors refer to this as "coalescing" of the two photons.

Now, considering this "bunching" or "coalescing" tendency of photons -- it seems to me that there should be a significant number of events where both dots are registered in the same pixel or in nearby pixels, as compared to the case where they are far apart. But in fact, the authors actually discard cases where the two events are recorded near to each other, because they say that there is a tendency for one photon to spuriously excite nearby pixels as a result of the photon multiplication technology that they use:

"During the experiment, we noticed that the photoelectron multiplication can trigger another avalanche in the neighboring channel, hence we had to reject the events where the distance between photons including both directions were smaller than twelve pixels of sCMOS detectors".

So my question is, IF this technology problem could be solved, and IF we could then include near by pixel pairs and also include the case of two photons in one pixel, -- then would we notice a spatial bunching tendency as part of the ideal theoretical behavior?

Last edited: Apr 29, 2016
2. May 4, 2016