International Exchange Award: Thin-film lithium niobate integrated photonics for photonic quantum technologies

The primary focus of the visit was to explore the untapped potential of Thin-Film Lithium Niobate (TFLN) Photonic Integrated Circuits (PICs) for next-generation quantum technologies. The visit marked a significant step toward a high-impact collaboration in the field of integrated quantum photonics.

TFLN has emerged as a “goldilocks” material for photonics due to its strong Pockels effect, low optical loss, and high confinement. Unlike traditional silicon photonics, TFLN allows for ultra-fast electro-optic modulation and efficient non-linear frequency conversion, which are critical for manipulating quantum states of light.

The discussions centred on leveraging the unique strengths of both institutions to address two major pillars:
– Quantum Computing: Developing scalable architectures for linear optical quantum computing, where TFLN’s high-speed switches can route single photons with minimal loss.
– Quantum Sensing: Utilising the material’s non-linear properties to create squeezed light sources and highly sensitive interferometers for precision measurement.

By combining Imperial’s expertise in quantum systems with ETH Zurich’s world-leading capabilities in nanofabrication and non-linear optics, the teams aim to overcome current bottlenecks in device efficiency and integration. This partnership signals a concerted effort to move quantum photonics from proof-of-concept laboratory setups toward robust, chip-scale platforms.

Benefits to the UK materials and quantum community

The visit fits with M4QN’s core mission to “ensure the UK harnesses internationally-leading materials research” to deliver a future quantum economy. M4QN specifically identifies efficient photonic integration and nanofabrication of solid-state devices as top-priority “roadmapping” challenges. By collaborating with ETH Zurich—a global leader in Thin-Film Lithium Niobate (TFLN) fabrication—Raj is bringing world-class manufacturing insights back to the UK, directly supporting M4QN’s goal of creating a “sustainable pipeline for quantum device development.

TFLN is a key “enabling material” for the UK’s National Quantum Strategy. This visit facilitates the transfer of high-performance chip designs from the lab to functional prototypes, a major hurdle for UK startups and academic groups. This exchange strengthens the UK’s pool of expert researchers who can bridge the gap between fundamental materials science and quantum system engineering.

By establishing a formal link with ETH Zurich, the UK community gains access to specialised nanofabrication techniques not yet fully scaled within the UK, ensuring our researchers remain at the frontier of Quantum Computing (scalable routing) and Quantum Sensing (precision interferometry). This collaboration serves to bypass domestic infrastructure bottlenecks and bolster the UK’s leadership in quantum photonics.

Visit Outcomes

Raj writes that the following objectives were achieved by the visit:

-Raj’s group established a comprehensive technical baseline of ETH Zurich’s state-of-the-art TFLN fabrication capabilities. This understanding allows for more streamlined device design cycles.
– Imperial PhD researcher Yazeed Alwehaibi gained hands-on expertise in characterising TFLN test devices. This direct exchange is instrumental in establishing a testbed at Imperial, ensuring parity in measurements between the two institutions.
– Collaborative design sessions focused on two primary frontiers. Firstly, scalable photonic quantum computing by developing integrated circuits with high-speed electro-optic modulators (EOMs) for low-latency photon routing. Second, enhanced quantum sensing via on-chip, loss-tolerant sensors that exploit the strong chi-2 non-linearity of Lithium Niobate for precision measurements.
– The teams identified specific joint funding avenues to provide long-term funding for these and future projects.