Scientists have demonstrated that a superconducting detector called a transition edge sensor (TES) is capable of counting the number of as many as 1,000 photons in a single pulse of light with an accuracy limited mainly by the quantum noise of the laser source. The findings, which are being prepared for publication, could eventually find use in quantum information processing, telecommunications and optical metrology at low light levels when information is embodied in readily detectable numbers of photons.
“When the uncertainty of the photon-number determination is sufficiently low and the detection efficiency is close to unity, by detection one can decode information that was encoded in the amplitude (photon number) of a pulse of light,” says Thomas Gerrits of PML Many detectors can sense single-photon pulses, and some (including the TES) can even resolve a few tens of photons in a single pulse. Accurate counts above approximately 50 photons, however, have not been achieved until now. The new PML research extends the photon-number resolution range as high as 1,000 and dramatically decreases the associated measurement uncertainties.