New Technologies for Scalable Single-Photon Detectors

Superconducting nanowire single-photon detectors (SNSPDs) offer unique performance characteristics. They can detect extremely weak optical signals down to the single-photon level across a broad wavelength range from the visible (VIS) to the mid-infrared (MIR), while providing very high detection speeds and quantum efficiencies, often exceeding 90%, as well as extremely low noise.

These capabilities enable new applications and enhance the performance of existing ones, particularly in quantum technologies such as quantum computing, quantum sensing and quantum communication, as well as in conventional communications, astronomy and remote sensing, biophotonics and many other fields. A key factor is the scalability of the number of pixels in single-photon detectors.

A consortium of companies and research institutions from Thuringia is addressing this challenge. Important steps towards multichannel detector instruments include reproducible, wafer-scale fabrication technologies for ultrathin, disordered superconducting niobium titanium nitride (NbTiN) layers for SNSPDs; the multilayer integration of SNSPDs with superconducting and, in particular, optical structures incorporating waveguides (Si/SiO or Si/SiN); suitable nanostructuring processes; and the optimization of layer interfaces. These technologies are being combined with new concepts for coupling to optical fiber bundles and their cryogenic integration.

Leibniz IPHT focuses primarily on researching the required fabrication and integration technologies. The targeted innovations will also provide a basis for photonic integrated circuits (PICs) that hybrid-integrate superconducting circuit structures and optical components on a single chip to enable novel functionalities.

The project is funded by the Free State of Thuringia under grant number 2025 VFE 0095 and co-financed by the European Union through the European Regional Development Fund (ERDF).