Gigahertz Detection Rates and Dynamic Photon-Number Resolution with Superconducting Nanowire Arrays

G. V. Resta, L. Stasi, M. Perrenoud, S. El-Khoury, T. Brydges, R. Thew, H. Zbinden, and F. Bussières

Nano Letters, 23(13), 6018-6026 (2023)

This work was a collaboration between the Quantum Technologies group at the University of Geneva and ID Quantique, also based in Geneva.

You can read the full article here, with the open access version here.


Many quantum technologies based on optics require the high-speed, high-efficiency detection of single photons. To this end, superconducting nanowire single-photon detectors (SNSPDs) have revolutionised optical quantum information processing. However, in their simplest implementation, SNSPDs are only able to distinguish 'zero' from 'many' photons; they cannot distinguish e.g. one photon from two photons. This lack of photon-number resolution (PNR) capability hinders our ability to take full advantage of techniques such as linear optic quantum computing (LOQC) and Gaussian boson sampling (GBS).


In our most recent paper, the team - in collaboration with ID Quantique - designed, engineered, and implemented a novel SNSPD array comprised of 14 independent pixels, with each of these pixels acting essentially as its own single-photon detector. This enables the device to support PNR capability as, for example, if two photons were incident on the array at the same time, two different pixels can each detect one of the photons. The figure to the right shows a scanning electron microscopy (SEM) image of the detector array itself, where the 14 pixels are arranged in an interleaved geometry.

The team demonstrated the exceptional qualities of the detector, including a maximum system detection efficiency of 90%, and its ability to operate in extremely high pulse rate regimes, showing a maximum count rate of 1.5 giga counts per second. The team were also able to demonstrate the photon number resolving capabilities of the device by reconstructing the photon number statistics incident on the device.

These developments could find immediate application in LOQC protocols, as well as being used in future GBS experiments.