# Leiden University develops superconducting detector capable of resolving individual photon numbers

- Published: 2026-11-06 15:08 UTC
- Section: Digital & Computing › Quantum technology
- Tags: superconducting nanowire detector, single photon counter, optical quantum computing, Leiden University, photonic qubits, Erik Baalbergen
- URL: https://realtech.media/news/rt-c8d0ca60f3d47264e731815b_leiden_university_develops/

**Physicists built a prototype superconducting nanowire sensor that counts discrete photons to improve optical quantum computing.**

![Leiden University develops superconducting detector capable of resolving individual photon numbers](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/842ae0b28a51b804.webp)
*Interesting Engineering*

Physicist Erik Baalbergen at Leiden University developed a superconducting light detector prototype capable of distinguishing between one, two, and three or more individual photons, according to Interesting Engineering [1]. The development took place as part of his doctoral research defended in the Netherlands alongside theoretical physicist Ilse Kuijf and master's student Lars Seldenthuis [1]. The system aims to resolve a critical limitation in photonic data processing by recording not only the presence of light, but also the exact photon count arriving at the sensor surface [1].

## Nanowire response and signal processing

The detection mechanism relies on superconducting nanowires operated at temperatures near absolute zero, where electrical resistance drops to zero [1]. When an incoming photon strikes an ultrathin wire, it perturbs the superconducting state and produces a measurable electrical pulse [1]. The research team modified the physical interface between the nanowire detector and its readout electronics, which reduced signal loss during transmission [1].

Rather than relying solely on the amplitude of the output pulse, the researchers analyzed the evolution of each signal over time [1]. This temporal profile analysis allows the instrument to determine the precise quantity of incident particles while indicating the statistical certainty of each measurement without requiring additional complex electronics [1].

## Integration with optical quantum hardware

While optical quantum computers execute most computational routines at room temperature using photons as qubits, their measurement stages still depend on cryogenic detectors [1]. The ability to count single photons directly affects the fidelity of state measurements during computational tasks [1].

During the project, Baalbergen collaborated with Dutch hardware developer QuiX Quantum, which introduced a functional optical quantum computer prototype in 2026 [1]. According to the researchers, implementing time-resolved superconducting nanowire arrays will support higher calculation accuracy in commercial optical processors targeting chemical reaction modeling and material synthesis simulations [1].

## Sources

1. [Interesting Engineering](https://interestingengineering.com/science/quantum-detector-distinguish-particles)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-c8d0ca60f3d47264e731815b_leiden_university_develops/