A light spectrometer including a laser configured to provide for a laser pulse (12), a quantum dot (30), an objective (21) configured to focus the laser pulse (12) onto the quantum dot (30) such that a fluorescent light beam is emitted from the quantum dot (30), a blazed grating (40) arranged in a light path of the fluorescent light beam to generate a plurality of fluorescent light beams of different wavelengths, an imaging lens (26) configured to generate a plurality of images from the fluorescent light beams of different wavelengths, respectively, a single photon avalanche diode (SPAD) array (50) having a plurality of pixels arranged at the imaging plane of the images, a circuit interfaced with the SPAD array, the circuit configured to detect a first photon and a second photon of an entangled photon pair emitted by the fluorescent light beam of the quantum dot in response to the laser pulse (12), wherein each pixel of the SPAD array is arranged to be aligned with a respective one of the plurality of images.