NIST scientists have developed a superconducting detector called a transition edge sensor (TES) that can accurately count the number of photons in a single light pulse. The TES, made of a 20 nm thick tungsten film, can detect photons by measuring the slight change in electrical resistance caused by the absorption of light energy.
The researchers found that the TES can reliably count up to 1,000 photons in a single pulse, with a model accurately describing the results of 20,000 individual tests. This breakthrough could enable low-light-level homodyne detection for optical quantum states, which requires high detection efficiency and low uncertainties.
The team is planning to develop this detection scheme in the near future, as it could be useful for states generated in the telecom band. Expanding the dynamic range of single-photon detectors advances a long-standing goal: to develop radiometric metrology tools that allow for more direct and better connections between existing radiometric standards and single-photon metrology standards.
The scientists are now examining ways to reduce the photon-number uncertainty even further, potentially using a light source that can dependably produce a highly exact number of photons, such as parametric down conversion (PDC).
Source: https://www.nist.gov/news-events/news/2011/11/adding-photons-tes
Keywords: photon, superconducting, metrology, radiometric, uncertainty
