Groundbreaking on-demand single photons at telecom wavelengths
Researchers from the University of Stuttgart and the Julius-Maximilians-Universität Würzburg, led by Prof. Stefanie Barz, have demonstrated a single-photon source that operates on demand at telecom wavelengths and achieves record performance. This breakthrough addresses a central challenge in quantum communication: delivering reliable, on-demand photons compatible with existing fiber networks. By generating photons directly at telecom frequencies, the system can minimize losses and maximize compatibility with standard optical infrastructure.
Why telecom wavelengths matter for quantum networks
Quantum communication hinges on robust, scalable photon sources. Telecom wavelengths (roughly 1300–1550 nm) are ideal for long-distance fiber transmission due to low loss in optical fibers and compatibility with established telecom components. A source that can produce single photons on demand at these wavelengths reduces the gap between laboratory demonstrations and real-world quantum networks. The work by Barz and colleagues marks a meaningful step toward practical quantum repeaters, secure quantum key distribution, and photonic quantum computing over existing fiber lines.
On-demand operation: a key performance leap
Traditional single-photon sources often rely on probabilistic processes, yielding photons only sporadically or requiring post-selection, which complicates integration into quantum protocols. The Stuttgart-Würzburg team reports an on-demand mechanism, where a trigger event reliably initiates a single-photon emission at a well-defined time. This temporal control is crucial for synchronizing photons across network nodes and for interfacing with quantum memories that may reside in different parts of a quantum information system.
Technical approach and what makes it record-breaking
While the exact experimental details are published in their paper, the essence lies in the careful engineering of the light-matter interaction within a solid-state or atomic-like system, tuned to emit photons precisely at telecom wavelengths. The researchers optimize factors such as emission efficiency, spectral purity, and indistinguishability between successive photons. Achieving high indistinguishability while maintaining on-demand timing at telecom wavelengths represents a challenging balance, and the reported results indicate a new benchmark in this domain.
Implications for quantum communication and beyond
The advent of on-demand telecom-wavelength single photons has several immediate implications. In quantum communications, it can simplify the construction of robust networks, enabling longer-distance transmission with fewer repeater nodes and lower loss. In quantum sensing and metrology, reliable single-photon sources at telecom frequencies open avenues for high-precision measurements in fiber-based setups. Moreover, the work strengthens the collaboration between university labs and industry pipelines that aim to translate laboratory breakthroughs into deployable technologies.
Next steps and broader context
Looking ahead, researchers will likely focus on scaling the source to higher repetition rates, integrating with quantum memories and photonic circuits, and examining the long-term stability required for field deployments. The collaboration between Stuttgart and Würzburg exemplifies how cross-institutional teams can push the boundaries of quantum photonics, combining materials science, quantum optics, and engineering expertise. As the field progresses, on-demand telecom-wavelength single photons may become a foundational component of secure communication networks and future quantum technologies.
About the researchers
The project is led by Prof. Stefanie Barz at the University of Stuttgart, with contributions from researchers at Julius-Maximilians-Universität Würzburg. Their work reflects a growing momentum in Germany’s quantum research ecosystem, aiming to translate laboratory insights into practical quantum-enabled communications.
