# Paderborn University detector counts 276 photons per pulse with sub-photon error in lab test

- Published: 2026-11-14 13:43 UTC
- Section: Science › Instruments & experiments
- Tags: photon counting, SNSPD, multiplexed detector, photon-number resolution, optical power meter, Paderborn University, photonic quantum computing, sub-photon precision, arrival-time histogram
- URL: https://realtech.media/news/rt-ede513523cbe79cf7961bdff_paderborn_university_detector/

**Paderborn University team combined superconducting nanowire detectors with multiplexing in a laboratory test on laser pulses, bridging single-photon counters and optical power meters.**

![Paderborn University detector counts 276 photons per pulse with sub-photon error in lab test](https://realtech.media/media/2026/11/df1e19552209a2be.jpg)
*National Institute of Standards and Technology, Wikimedia Commons, Public domain*

Researchers at Paderborn University in Germany have developed a detection platform that counts from zero to more than 9,000 individual photons in optical pulses, according to bioengineer.org. The experimental work was reported in Optica. The platform pairs superconducting nanowire single-photon detectors (SNSPDs) with optical multiplexing, creating 1,024 discrete detection bins and relying on an accurate model of detector behavior [1].

## Why single-photon counters and power meters do not overlap

Conventional single-photon detectors, including avalanche photodiodes, typically register only whether light is present or absent, not how many photons arrived [1]. Photodiodes built for high-intensity pulses suffer from electrical noise that obscures single-photon fluctuations. As a result, they cannot resolve photon number at low to intermediate levels [1].

SNSPDs offer low intrinsic noise, high timing resolution and high detection efficiency. Earlier studies showed that a single SNSPD with high-precision timing electronics can resolve only a limited number of photons. The Paderborn team therefore tested whether this intrinsic photon-number resolution could be combined with multiplexing on a scale an order of magnitude larger than in previous counting systems [1].

## Multiplexing into 1,024 bins

The architecture divides an incoming light pulse into 128 smaller pulses spread sequentially in time. These segments are directed across eight superconducting detectors, giving 1,024 separate detection bins that share the original photons [1]. Model-informed characterization of the hardware allowed the researchers to extract precise photon counts [1].

For testing, the team used laser pulses calibrated to average between 1 and 15,000 photons per pulse. The calibrated instrument counted photons in pulses containing up to 276 photons with an uncertainty of less than one photon [1]. According to the research team, a conventional multiplexed device without the model-informed approach would need about 37,000 detector units for equivalent precision, versus 1,024 bins here [1].

The detectors also produce arrival-time histograms that map the photon-number resolution of the system. Timon Schapeler explained that counting accuracy degrades as the number of photons grows, which is why multiplexing and intrinsic resolution must be combined. Tim Bartley said that large-scale measurement of individual photons underpins single-photon-level imaging and photonic quantum computing [1].

This first study used classical laser pulses. The authors plan to extend the platform to bright quantum states of light to study quantum effects at larger scales [1].

## Sources

1. [bioengineer.org](https://bioengineer.org/multiplexed-superconducting-detectors-precisely-count-more-than-9000-individual-photons/)
2. [Interesting Engineering](https://interestingengineering.com/science/photon-counting-detector-paderborn-university)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-ede513523cbe79cf7961bdff_paderborn_university_detector/