NIST: superconducting single-photon detectors up to 0.1 mm wide reach the material’s performance limit and dark counts drop by 10 orders of magnitude
On 24 August 2026 the US National Institute of Standards and Technology (NIST) described superconducting nanowire single-photon detectors (SNSPDs) with wires up to 0.1 mm wide, more than a hundred times wider than the typical 100 nm. The results were published in Optica on 19 August 2026.
- In an SNSPD a photon creates a hot spot in the superconducting wire that disrupts the current and produces a voltage pulse. NIST had earlier brought such detectors to 98% detection of incoming photons, but their nanoscale width requires specialised fabrication, and defects crowd the current at the wire edges, which limits the bias current and increases false counts (dark counts).
- The team placed current-biased superconducting “rails” on both sides of the detector; their magnetic field spreads the current evenly across the wire width. This allows in-situ tuning of the detector into a regime limited only by material quality and, according to the Optica paper, reduces the dark count rate by 10 orders of magnitude.
- The material performance limit was shown for wires up to 0.1 mm wide, and for a 20 µm wide detector — twenty times wider than the previous state of the art — near-unity internal detection efficiency at a wavelength of 4 µm. The wide detectors are polarisation-insensitive.
- According to NIST it is not yet clear whether wide detectors can reach the 98% efficiency of their nanoscale counterparts — more testing is needed. The simpler design is expected to make large detectors and arrays easier to manufacture, among others for astronomy; SNSPDs are also used in quantum and deep-space communication. The paper (Optica, vol. 13, no. 8, p. 1649) is by K. Parzuchowski, E. Mueller and colleagues.
Source: NIST — NIST Researchers Supersize Quantum Technology to Help Detect Faint Photons (24.08.2026)