The Broadband Quantum Synthesizer (BQS) project is a UK-Canada collaboration advancing the frontier of ultrafast quantum photonics. Supported by Innovate UK with funding of £450,000, the project commenced in September 2023 and will run for two years. Its goal is to develop the world’s first packaged source of ultra-broadband squeezed light pulses, a tool vital for next-generation quantum technologies in sensing, communication, and imaging.
The BQS project leverages complementary expertise from across the UK and Canada:
- Few-Cycle Inc. provides the core FOPA (Fourier-plane Optical Parametric Amplification) platform and will lead the project and system integration.
- Covesion contributes its advanced capability in custom-engineered PPLN crystals with spatially varying poling periods, critical to phase-matching across the Fourier plane.
- The University of Glasgow and NRC Canada will co-develop and validate the system in cutting-edge experiments such as quantum-enhanced high harmonic generation and squeezed light frequency conversion.
At the heart of the BQS initiative is the development of squeezed light pulses with durations under 100 femtoseconds (fs), ideally as short as 40fs, achieving >3dB of quantum noise reduction. These “squeezed” light states are entangled fields of photons that surpass classical light in sensitivity and information capacity. They form the basis of quantum metrology, enabling measurements with unprecedented precision in spectroscopy, microscopy, and imaging, and are crucial to quantum communication and computation systems.
Although it is possible to generate high degrees of squeezing (>15dB) using continuous waves or long pulses, no practical solution currently exists for producing broadband, highly squeezed light at ultrafast timescales. This is a major limitation for advanced quantum applications, particularly in bio-imaging, where biological events occur at femtosecond timescales. The BQS project aims to fill this gap with a compact, reliable source.
The BQS system will be built around an innovative approach known as Fourier-plane, non-linear Optics. This technique, patented and exclusively licensed to Few-Cycle Inc. (US Patent 9,910,339), overcomes the longstanding trade-off between gain and bandwidth that has hampered progress in ultrafast squeezed light generation. In this system, ultra-broadband pulses are spectrally decomposed in the Fourier plane of a pulse shaper. Each narrowband spectral slice is individually amplified in a spatially multiplexed non-linear crystal, specifically, Periodically Poled Lithium Niobate (PPLN) crystals developed by Covesion. These slices are subsequently recombined, yielding a short, highly squeezed pulse across a wide bandwidth (targeting >100nm, and up to 300nm in future prototypes).
This architecture allows for phase-matched, independent manipulation of each frequency component, circumventing the constraints of traditional parametric amplification techniques and enabling generation of squeezed pulses with durations under 100fs, potentially reaching 40fs.
The successful development of the BQS system will provide an essential building block for continuous-variable quantum optics, a domain where macroscopic entanglement among billions of photons powers the most sensitive measurements known today. Applications include:
- Quantum-enhanced non-linear microscopy, enabling detection of weak biological signals with greater precision.
- Secure communications, by embedding squeezed light into quantum key distribution systems.
- Quantum computation, especially in architectures utilising continuous-variable states.
- Quantum spectroscopy, offering access to ultrafast molecular dynamics with previously unreachable resolution.
The system will also be validated for quantum attosecond spectroscopy, a newly emerging field requiring squeezed pulses with extreme temporal and spectral precision.
The BQS platform will have three primary commercial outputs:
- A stand-alone quantum synthesiser for research and industrial labs.
- A next-generation optical parametric amplifier for microscopy and material processing.
- Sub-components such as fan-out PPLN crystals, extending Covesion’s product line for the global QT supply chain.
Furthermore, the project is expected to generate new intellectual property (IP) and performance data, laying the groundwork for future products and market entry.
The BQS project exemplifies the spirit of UK–Canada bilateral cooperation in quantum technologies. With combined government and industry funding pledges exceeding £1 billion to support quantum collaboration, the project supports the strategic aim of transitioning cutting-edge quantum science into real-world, accessible tools. By merging expertise from academia and industry, the project sets the foundation for scalable photonic quantum systems, pushing the boundaries of what’s possible in sensing, communication, and biological imaging.
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