Top-down solid-state systems for quantum sensing using silicon, photonics, and robotics

In both cellular biology and chemistry, many critical processes that affect our quality of life are not yet well understood. These processes happen within systems surrounded by high levels of environmental noise. Enter the nitrogen-vacancy (NV) defect in diamond — an ambient atom-like probe that yields single photons, particles of light, correlated with its spin property. Capturing single photons enables the spin-based sensor to function as an extremely sensitive monitor of its immediate environment, as information can now exit the environment, free from electromagnetic disruption. This quantum sensing technology has already provided a unique window on processes within cellular structures and chemical reactions. There is now over a decade of scientific evidence that this technology would transform areas where classical techniques have stalled and there is unmet demand. However, to date, these sensors are constrained to physics laboratories with complicated optics, mechanics, and associated infrastructure. They cannot be used at scale or by non-physicists who would benefit from this transformative technique. In my fellowship, I will take the tools used to produce computer chips to level-up this solid-state sensor. Semiconductor tools, refined over half a century to possess unmatched control and yield, would evolve solid-state spin-based techniques into manufacturable, robust, low-power, and ultimately low-cost sensors by: (i) lithographically depositing diamond in micron-scale regions to realise a 64-pixel spin-based sensor array (the current state-of-the-art is two pixels), (ii) routing pixel information at micron-scale densities using manufactured silicon photonics, (iii) using robotics in new ways to produce milliradian-accurate fields to sensitise these systems where current vector magnet technology fails (iv) combining the above with silicon microelectronics to extract and process nanosecond sensor information at unprecedented efficiencies. The primary aim of my fellowship is to demonstrate a manufacturable spin-based sensor to replace bulky experiments: routing and controlling an optically-active defect using foundry photonics, microelectronics and robotics, making the sensor smaller and therefore more accessible. My secondary aim is to unlock improved sensitivity through robust control, photonic enhancement and quantum enhancement. The objectives to achieve these aims are as follows: Photonic integration of the sensor: the rise of silicon quantum photonics has shown that commercial foundries are the most reliable way to achieve scale and robustness in quantum experiments. Co-integration of precise robotics to provide robust three-dimensional field alignment. Quantum-enhanced readout: engineering the spin energy levels with the precise field produced by the robot removes non-spin-conserving emission. This allow photonics to increase the sensor readout rate. Benchmarking performance against the commercial spin-based sensors offered by Project Partners to demonstrate the benefit of this scalable technology. Full-stack design of control and user interface. Broad usability feedback to ensure the sensor is ready to move forward into commercialisation by fellowship end. By fellowship end, I will use the newly-manufacturable quantum sensor to demonstrate two key real-world applications: mapping signals in a single biological cell to gain insight into disease pathways and imaging a single molecule, an important advance for nanolitre chemical analysis to replace bulky spectroscopy apparatus. Collaborating with the pioneering researchers in this field and those experienced in developing market-ready products, we will take the steps that put solid-state spin-based sensors into both the hands of medical practitioners, where adoption has the potential to enable precision in disease diagnosis, and research chemists, developing clearly scalable use cases in spectroscopy across the chemical industry.