A system includes an Alice transmitting terminal, a wavelength division multiplexing (WDM) unit and a plurality of Bob terminals for receiving a plurality of photons of different wavelengths; the Alice terminal is connected with the plurality of Bob terminals by the WDM unit; the Alice terminal includes a multi-wavelength laser generation device, an attenuator, a first polarization beam splitter, a first beam combiner, a phase modulator, a first polarization controller and a second polarization controller; the WDM unit includes a wavelength selection device; each Bob terminal includes a second polarization controller, a third polarization controller, a fourth polarization controller, a third polarization beam splitter, a fourth polarization beam splitter, a second beam combiner, a third beam combiner, a first photon detector, a second photon detector, a third photon detector and a fourth photon detector.