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Multiphoton coincidence camera with high temporal resolution

Periodic Reporting for period 1 - gammaCam (Multiphoton coincidence camera with high temporal resolution)

Reporting period: 2019-05-01 to 2020-07-31

GammaCam aimed at investigating the two single photon avalanche diode (SPAD) array sensors, that were developed within the frame of the SUPERTWIN project: SuperEllen and SuperAlice. The first one, SuperEllen, was developed as a precursor of the second one SuperAlice, that has a high number of pixels, making it a state-of-the-art single photon imager. The sensors were developed for the detection of entangled photons, however they a are unique in their capabilities of detecting the spatio-temporal coincidences between multiple photons at short time scales. Those SPAD array sensors thus offer the possibility to measure higher order correlations of the light field, where usual cameras only measure intensities. However, the applications of such correlations measurements for imaging are still rare, in part because of the absence of suitable detectors. It was hence important characterize the capabilities and limitations of those novel sensors, in order to investigate their broader applications; and to compare them with already existing sensors.
Developing new tools for imaging is of relevance for many fields of science and technology going from range measurements (3D imaging) to new microscopy methods.
While SuperEllen was functional at the end of the SUPERTWIN project, SuperAlice was only ready at the end of the project, with a still to be finalized firmware. Therefore, within gammaCam we, in parallel, pursued the development of SuperAlice while investigating both sensors for various applications.
In order to make the sensors available for various applications and potentially for other researchers, we develop a first prototype of a camera, including a case for the sensors and its board together with standard optical and electrical connections. The firmware was improved in order to optimize the frame rate of the SuperAlice and the acquisition and processing software was developed to be able to treat the large amount of data when measuring higher order correlations.
The developed sensor was used different experiments: characterization of entangled photon pairs, high rate single photon counting, fluorescence lifetime imaging and high dynamic range imaging. The results were published in a peer reviewed journal and presented in several conferences.
In parallel a comparison between the performances of the sensors and of selected commercial cameras has been realized, showing that the new sensors are particularly good at measuring correlations between several photons at arbitrary times.
Finally, an estimate of the cost of production of small series of the camera was done.
We demonstrated that the sensors are able to measure correlations in entangled photon pairs, as efficiently as commercial cameras. Thanks to their high temporal resolution, we expect them to be able to detect correlations between more than 2 photon even more efficiently compared to other available sensors. While source of photon pairs are already easily available, multiple entangled photons are still hard to generate. However, the present sensor would be of great use when such sources are ready. In addition the multifunctionality of SuperAlice makes it attractive for research laboratory, as various types of experiment could be performed without changing of camera.
First prototype of the camera