A laser-based quantum source generates the randomness in Tropos - quantum random number generator (QRNG). To elaborate on the process, a laser produces a stream of the elementary particle, photon. The photons generated from the laser are used to generate the random numbers using the "Time-of-Arrival" of the single photons on the single photon detector.
The following diagram depicts the process from photon generation to random number output. The process starts with the generation of light from a laser source, which is converted into single-photon level using variable optical attenuators. The photons are then sent onto a SPD (Single Photon Detector) where the detection time bin of the photon is recorded using external time reference.
The photon has a uniform probability of hitting any particular time bin. No one knows behorehand in which particular time bin the detection will happen even if all the parameters about the state preparation, state propagation, and detection are revealed. It is during the detection instant, photon collapses to one particular time bin.
The test suits check the randomness of the bits. Only if the conditions are met, they are forwarded to the applications or users requesting the random numbers.
RESTful interface is the typical API used for the transfer of random numbers from Tropos to external applications or end users.