New material boosts prospects of ultra fast single photon detector
1 min read
By swapping one superconducting material for another, researchers at the National Institute of Standards and Technology (NIST) have found a practical way to boost the efficiency of the world's fastest single photon detector, while also extending light sensitivity to longer wavelengths.
The researchers say the new tungsten silicon alloy could make the ultrafast detectors more practical for use in quantum communications and computing systems, experiments testing the nature of reality, and emerging applications such as remote sensing.
The detector, made of superconducting nanowires, has an efficiency rating of 19 to 40% over a wavelength range of 1280 to 1650nm. According to the scientists, its limitations are due mainly to imperfect photon absorption, suggesting that, with further design improvements, detector efficiency could approach 100% reliably.
The tungsten silicon alloy was selected mainly because it had a higher energy sensitivity, which resulted in more reliable signals. The researchers witnessed that a photon broke more electron pairs in the silicon alloy compared to niobium nitride and said it had a more uniform and less granular internal structure, making the nanowires more reliably sensitive throughout.
As a result of the higher energy sensitivity, the tungsten silicon nanowires had larger dimensions (150nm wide versus 100nm or less for niobium nitride), which enlarged the detectors' functional areas to more easily capture all photons.
The NIST team now hopes to raise the efficiency of tungsten alloy detectors by embedding them in optical cavities, which trap light for extremely high absorption. It believes high efficiency may enable the use of nanowire detectors in demanding applications such as linear optical quantum computing, which encodes information in single photons.
