10143484QAPTCHA - Quantum Atom-based Positioning for Train Control with a Hybrid AccelerometerActiveCollaborative R&DInnovate UKQuantum sensing technologies offer levels of measurement precision, accuracy, and stability that exceed those offered by classical (or non-quantum) approaches. An area where this performance enhancement shows great potential is in positioning, navigation and timing (PNT) systems. An important subcategory of PNT systems are ones based on inertial navigation systems. These calculate a relative position from a known starting point based on continuous measurements of acceleration, rotation, and time. Such systems are essential in environments where satellite navigation systems are either unavailable, such as when underground or underwater, or when they are actively denied. Precise positioning is a safety-critical component of the rail network, which currently relies on expensive trackside infrastructure and onboard equipment rather than satellites which can be unreliable in tunnels and rural areas. Future network upgrades will require new reliable and affordable PNT technologies beyond the capabilities of classical devices alone. Currently, the long-term positioning accuracy of such systems is severely limited by the performance of the classical acceleration sensors that they use, even in state-of-the-art incarnations. The performance of acceleration sensors based on atom interferometry with ultra-cold atoms offer at least an order of magnitude improvement on the long-term positioning accuracy of such classical inertial navigation systems. Despite this potential, quantum sensors cannot compete with the high frequency measurements of classical sensors. By combining quantum and classical acceleration sensors within a single unit to form a hybrid device, we can get the best of both worlds - high frequency measurements and long-term accuracy. There are currently no commercially available products that deliver the benefits of cold atom acceleration sensing. Harnessing the power of additive manufacturing (AM), commonly referred to as 3D printing, our project will enable the delivery of an economical hybrid sensor with components suitable for mass production. Using designs optimised for AM, complex structures not possible with conventional techniques can be engineered to reduce the size, weight, and costs of the devices without sacrificing performance, making them more commercially attractive to customers. Our project will make significant progress towards demonstration of commercial viability through performance evaluations of our hybrid acceleration sensor on a moving vehicle.