Efficient Single Photon Detection from 500 nm to 5 μm Wavelength

We report on superconducting nanowire single photon detectors (SNSPDs) based on 30 nm wide nanowires with detection efficiency η ∼ 2.6–5.5% in the wavelength range λ = 0.5–5 μm. We compared the sensitivity of 30 nm wide SNSPDs with the sensitivity of SNSPDs based on wider (85 and 50 nm wide) nanowires for λ = 0.5–5 μm. The detection efficiency of the detectors based on the wider nanowires became negligible at shorter wavelengths than the 30 nm wide SNSPDs. Our 30 nm wide SNSPDs showed 2 orders of magnitude higher detection efficiency (η ∼ 2%) up to longer wavelength (λ = 5 μm) than previously reported. On the basis of our simulations, we expect that by changing the optical coupling scheme and by integrating the detectors in an optical cavity, the detection efficiency of our detectors could be increased by a factor of ∼6

Single Photon Counting from Individual Nanocrystals in the Infrared

Experimental restrictions imposed on the collection and detection of shortwave-infrared photons (SWIR) have impeded single molecule work on a large class of materials whose optical activity lies in the SWIR. Here we report the successful observation of room-temperature single nanocrystal photoluminescence at SWIR wavelengths using a highly efficient multielement superconducting nanowire single photon detector. We confirm that the photoluminescence from single lead sulfide nanocrystals is strongly antibunched, demonstrating the feasibility of performing sophisticated photon correlation experiments on individual weak SWIR emitters, and, more broadly, paving the way for sensitive measurements of spectral observables on infrared quantum systems that are incompatible with current detection techniques