Photon-Number Discrimination from Increasing Time-of-Arrival Separation in Wide Superconducting Microstrip Single-Photon Detectors
Abstract
Measurements of photon-number-dependent time-of-arrival (TOA) distributions in wide NbN superconducting microstrip single-photon detectors (SMSPDs) are presented. Two \SI{10}{\um}-long devices with widths of \SI{3.2}{\um} and \SI{6.4}{\um} are characterized under pulsed \SI{515}{nm} excitation. The TOA histograms are described by sums of exponentially modified Gaussian (EMG) components, with the wider device exhibiting components assigned to photon numbers up to n=8. Adjacent TOA peaks become more distinguishable relative to their widths at higher photon number, in contrast to the compression of neighboring photon-number timing shifts observed in conventional narrow-wire SNSPDs. For the components assigned to n=7 and n=8, the FWHM-normalized peak separation is 2.15, and the fitted EMG distributions yield an equal-prior pairwise TOA-assignment fidelity of 99.6%. The EMG exponential-tail parameter τn decreases strongly with photon number, while the Gaussian-location parameter μn continues to shift between neighboring components. A phenomenological model motivated by absorption-site-dependent vortex processes and collective current redistribution captures these timing trends. These results support wide SMSPDs as a platform for TOA-based photon-number discrimination at high photon number, relevant to multiphoton-state characterization and photonic quantum information processing. The same geometry also provides a setting to examine how the spatial distribution of photon absorption affects vortex-assisted detection.
Related
- Enhanced electron-beam lithography to reduce the frequency scatter of 200-400 GHz superconducting microstrip resonators for on-chip filterbank spectrometers
- Diffusive Description of Superconducting Single-Photon Detectors Using Quantum Mechanics
- Experimental subdiffraction source discrimination enabled by spatial demultiplexing and single-photon detectors
- Characterization and Active Control of Position-Dependent Timing Dynamics in Superconducting Strip Single-Photon Detectors
- Pulse-shape discrimination with machine learning for CZT detectors at the DAΦNE beam test facility
BibTeX
@misc{wu2026photonnumber,
title = {{Photon-Number Discrimination from Increasing Time-of-Arrival Separation in Wide Superconducting Microstrip Single-Photon Detectors}},
author = {Hsin-Yeh Wu and Shu-Xiao Liu and Boris Tuchming and Xavier-François Navick and Pu-Kai Wang and Yi-Ren Wu and Jia-Wern Chen and Marc Besançon and Jean-François Glicenstein and Pisin Chen and Yu-Jung Lu and Stathes Paganis},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32154},
eprint = {2610.32154},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32154},
}
RIS
TY - UNPB
TI - Photon-Number Discrimination from Increasing Time-of-Arrival Separation in Wide Superconducting Microstrip Single-Photon Detectors
AU - Hsin-Yeh Wu
AU - Shu-Xiao Liu
AU - Boris Tuchming
AU - Xavier-François Navick
AU - Pu-Kai Wang
AU - Yi-Ren Wu
AU - Jia-Wern Chen
AU - Marc Besançon
AU - Jean-François Glicenstein
AU - Pisin Chen
AU - Yu-Jung Lu
AU - Stathes Paganis
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32154
UR - https://arxiv.org/abs/2610.32154
AB - Measurements of photon-number-dependent time-of-arrival (TOA) distributions in wide NbN superconducting microstrip single-photon detectors (SMSPDs) are presented. Two \SI{10}{\um}-long devices with widths of \SI{3.2}{\um} and \SI{6.4}{\um} are characterized under pulsed \SI{515}{nm} excitation. The TOA histograms are described by sums of exponentially modified Gaussian (EMG) components, with the wider device exhibiting components assigned to photon numbers up to n=8. Adjacent TOA peaks become more distinguishable relative to their widths at higher photon number, in contrast to the compression of neighboring photon-number timing shifts observed in conventional narrow-wire SNSPDs. For the components assigned to n=7 and n=8, the FWHM-normalized peak separation is 2.15, and the fitted EMG distributions yield an equal-prior pairwise TOA-assignment fidelity of 99.6%. The EMG exponential-tail parameter τ_n decreases strongly with photon number, while the Gaussian-location parameter μ_n continues to shift between neighboring components. A phenomenological model motivated by absorption-site-dependent vortex processes and collective current redistribution captures these timing trends. These results support wide SMSPDs as a platform for TOA-based photon-number discrimination at high photon number, relevant to multiphoton-state characterization and photonic quantum information processing. The same geometry also provides a setting to examine how the spatial distribution of photon absorption affects vortex-assisted detection.
ER -