A quantum flow cytometer detects an analyte with photon-number statistics and includes: a flow cytometer that receives a pump light, an analyte and produces scattered light from the analyte; an intensity interferometer that includes a beam splitter and receives the scattered light; splits the scattered light; and single photon detectors that receive the scattered light, such that the beam splitter and the single photon detectors provide photon number statistics that detects the analyte. A process for detecting the analyte with photon-number statistics includes: receiving the pump light; producing, by the analyte, scattered light from scattering the pump light; splitting the scattered light into first scattered light and second scattered light; detecting, by single photon detectors, the first scattered light and second scattered light; producing, by the single photon detectors, detection signals; and subjecting the detection signals to an analyzer to detect the analyte by photon number statistics.