Beyond single-photon counting

Neil J. Savage

Thomas Gerrits, Brice Calkins, Adriana E. Lita +3 more

We illuminate a photon-number-resolving transition edge sensor with strong pulses of light containing up to 6.7 million photons (0.85 pJ per pulse). These bright pulses heat the sensor far beyond its transition edge into the normal resistance regime. We show that the sensor operates from the single-photon-counting regime to picowatt levels of light and that the detection noise is below shot-noise for up to 1000 photons.

Thomas Gerrits, Brice Calkins, Nathan A. Tomlin +4 more

Typically, transition edge sensors resolve photon number of up to 10 or 20 photons, depending on the wavelength and TES design. We extend that dynamic range up to 1000 photons, while maintaining sub-shot noise detection process uncertainty of the number of detected photons and beyond that show a monotonic response up to ≈ 6 · 10(6) photons in a single light pulse. This mode of operation, which heats the sensor far beyond its transition edge into the normal conductive regime, offers a technique for connecting single-photon-counting measurements to radiant-power measurements at picowatt levels. Connecting these two usually incompatible operating regimes in a single detector offers significant potential for directly tying photon counting measurements to conventional cryogenic radiometric standards. In addition, our measurements highlight the advantages of a photon-number state source over a coherent pulse source as a tool for characterizing such a detector.

Yan Liang, Heping Zeng

Gerrits, Calkins Calkins, Tomlin +4 more