Single Photon Detectors | laboratorioattanasio

Superconducting films for Superconducting Single Photon Detectors (SNSPD & SMSPD)

contact carla.cirillo@spin.cnr.it

Superconducting Single-Photon Detectors are among the best established technology based on superconducting materials. Nevertheless, the community is continuously committed to improve the detector performances.

The group is intensively involved in this field of research, in particular in the development of innovative materils that can find application both as Superconducting Nanowire Single Photon Detectors (SNSPD) and Superconducting Microwire Single Photon Detectors (SMSPD)

The first SNSPDs based on NbRe films 8-nm-thick were realized in collaboration with TU Delft and its spin-off Single Quantum. NbRe films with their polycrystalline structure made of small crystallites, their disorder-dominated transport properties, and their relatively high value of the critical temperature are a promising alternative between the materials-of-choice such as NbN or NbTiN and amorphous superconductors.

The study reveals that the detectors performances in terms of time resolution, such as recovery times between about 8 and 19 ns and time jitter of about 35 ps, are competitive with many of the already employed materials.

NbReN films were recently suggested as an alternative material as well. Indeed, the microscopic properties of NbReN films which may produce improvement of some of the main figures of merit of NbRe-based detectors.

However, different applications require large area coverage, such as dark matter research or LIDAR. Therefore, efforts are made to increase the widths of the superconducting strips from the nanoscale, as in Superconducting Nanostrips Single Photon Detectors (SNSPDs), to micrometric scale, as in the recently proposed Superconducting Microstrips Single Photon Detectors (SMSPDs). Our recent activity on NbRe-based superconducting detectors was based on innovative microstrip layouts. We demonstrated that the devices can operate in the single photon regime at λ larger than telecom wavelength, up to 2 μm, and at temperatures easily achievable by commercial cryocooler systems.

Ejrnaes, M. et al. Single photon detection in NbRe superconducting microstrips. Appl. Phys. Lett. 121, 262601 (2022).
Ercolano, P. et al. Investigation of dark count rate in NbRe microstrips for single photon detection. Supercond. Sci. Technol. 36,
105011 (2023).