Quantum frequency conversion
Quantum computers, memories and sensors exchange information through light, each at its own wavelength. Optical fiber loses the light of the leading platforms within a few kilometers. Our converters shift that light to a common telecom wavelength, so different quantum devices can connect with each other over the fiber already in the ground.
Why conversion
The leading qubit platforms for quantum networks emit visible or near-infrared light. Standard fiber is built for the telecom band around 1550 nm and quickly loses light at shorter wavelengths.
photons arrive after 20 km of fiber at 854 nm
of 1,000,000 photons arrive after 20 km at 1550 nm
Without conversion, every quantum computer, memory and sensor stays an island. Our quantum frequency converters shift their photons to the telecom band, where the fiber transmits about 400,000 times more of them. That makes quantum frequency conversion a key technology for long-distance quantum links over standard optical fiber.
How it works
Quantum frequency conversion changes the color of a photon, not the information it carries. Think of a translator who changes the language but keeps the meaning.
A single photon from your qubit, memory or sensor enters the converter through a standard fiber.
Inside a special crystal, the photon meets a strong laser beam. Together they produce a photon at the telecom wavelength. Filters remove stray light so the single photon stays clean.
The photon travels through standard fiber with its quantum state intact. At the receiving end, a second converter shifts it back to the wavelength the quantum hardware needs.
Proven technology
Our team has already converted single photons from five different qubit systems to telecom wavelengths. This includes polarization-encoded qubits and a specialized two-stage conversion approach designed for ultra-low noise. Building on results across five different qubit systems, we aim to offer unprecedented flexibility in connecting quantum hardware.
Applications
Fiber loss limits how far quantum links can reach directly. Repeaters overcome this by connecting shorter segments through quantum memories. Most of these memories emit at short wavelengths, and conversion connects them to low-loss telecom fiber.
Linking quantum processors over fiber lets several smaller machines work as one larger computer. Conversion makes the photons that connect them fiber compatible.
Sensors and clocks that share entanglement can measure more precisely than any single device. Conversion connects them across buildings, cities and sites.
Entanglement-based links over existing fiber, with security rooted in physics. Relevant for critical infrastructure, government, defense and dual-use applications.
Campus and metro testbeds, research infrastructure and any other quantum network that runs over telecom fiber.
Any wavelength to any wavelength: match a photon source to a quantum memory of a different type, or shift photons to where single-photon detectors work best.
Readiness
Our converters do not stop at publications. We build systems tailored to our customers’ emitters today and are turning them into a standardized 19-inch platform that runs outside laboratory conditions.
Conversion published for five qubit systems and demonstrated over 33 km of telecom fiber.
Custom converter systems for research institutions and quantum hardware companies.
A standardized 19-inch unit with variants per emitter: fiber in, fiber out, temperature stable, built for 24/7 operation.
| Conversion wavelength | Customer specific | Any emitter wavelength to any visible, near-infrared or telecom wavelength |
|---|---|---|
| Efficiency | Up to 60 % today | Fiber to fiber, depending on wavelength; further optimization underway |
| Noise | Below 10 counts/s/GHz | Depending on wavelength and filter bandwidth |
| Coupling | Fiber in, fiber out | Single-mode, connectorized |
| Qubit encoding | Polarization or time-bin | Depending on your setup |
| Form factor | 19-inch rack unit | Target production housing |
Team
Managing Director Technology & Co-Founder
Built quantum frequency converters for neutral atoms, trapped ions, color centers and quantum dots, and co-authored the experiments behind all platform demonstrations above.
Managing Director Business & Co-Founder
Entrepreneur and deep-tech investor with hands-on experience in scaling, fundraising and company transactions, including the exit of his own company; leads finance, fundraising, business development and legal.
Head of Commercialisation & Co-Founder
Lead author of the two-stage, low-noise conversion from silicon-vacancy centers to the telecom C-band. His technical understanding underpins commercialisation and sales.
Head of Production & Co-Founder
Turns lab-bench conversion setups into rack-mounted, temperature-stable hardware that runs outside laboratory conditions; co-author of several publications.
Photos: Viktoriia Karakatsii
Scientific advisor
Professor of experimental physics at Saarland University with more than 20 years of experience in quantum frequency conversion, single-photon sources and quantum repeater architectures. Optiqal is a spin-out of his research group.
Photo: © Beate Wehrle, UdS
Scientific references
One result per qubit system, each co-authored by members of our team.
Contact
Write two lines about your setup or your partnership idea. We aim to answer within two working days.
