Sensors permeate our society, measurement underpins quantitative action and standardized accurate measurements are a foundation of all commerce. The ability to measure parameters and sense phenomena with increasing precision has always led to dramatic advances in science and in technology - for example X-ray imaging, magnetic resonance imaging (MRI), interferometry and the scanning-tunneling microscope. Our rapidly growing understanding of how to engineer and control quantum systems vastly expands the limits of measurement and of sensing, opening up opportunities in radically alternative methods to the current state of the art in sensing. Through the developments proposed in this Fellowship, I aim to deliver sensors enhanced by the harnessing of unique quantum mechanical phenomena and principles inspired by insights into quantum physics to develop a series of prototypes with end-users. I plan to provide alternative approaches to the state of the art, to potentially reduce overall cost and dramatically increase capability, to reach new limits of precision measurement and to develop this technology for commercialization. Light is an excellent probe for sensing and measurement. Unique wavelength dependent absorption, and reemission of photons by atoms enable the properties of matter to be measured and the identification of constituent components. Interferometers provide ultra-sensitive measurement of optical path length changes on the nanometer-scale, translating to physical changes in distance, material expansion or sample density for example. However, for any canonical optical sensor, quantum mechanics predicts a fundamental limit of how much noise in such experiment can be suppressed - this is the so-called shot noise and is routinely observed as a noise floor when using a laser, the canonical "clean" source of radiation. By harnessing the quantum properties of light, it is possible reach precision beyond shot noise, enabling a new paradigm of precision sensors to be realized. Such quantum-enhanced sensors can use less light in the optical probe to gain the same level of precision in a conventional optical sensor. This enables, for example: the reduction of detrimental absorption in biological samples that can alter sample properties or damage it; the resolution of weak signals in trace gas detection; reduction of photon pressure in interferometry that can alter the measurement outcome; increase in precision when a limit of optical laser input is reached. Quantum-enhanced techniques are being used by the Laser Interferometer Gravitational Wave Observatory (LIGO) scientific collaboration to reach sub-shot noise precision interferometry of gravitational wave detection in kilometer-scale Michelson interferometers (GEO600). However, there is otherwise a distinct lack of practical devices that prove the potential of quantum-enhanced sensing as a disruptive technology for healthcare, precision manufacture, national security and commerce. For quantum-enhanced sensors to become small-scale, portable and therefore practical for an increased range of applications outside of the specialized quantum optics laboratory, it is clear that there is an urgent need to engineer an integrated optics platform, tailored to the needs of quantum-enhanced sensing. Requirements include robustness, miniaturization inherent phase stability and greater efficiency. Lithographic fabrication of much of the platform offers repeatable and affordable manufacture. My Fellowship proposal aims to bring together revolutionary quantum-enhanced sensing capabilities and photonic chip scale architectures. This will enable capabilities beyond the limits of classical physics for: absorbance spectroscopy, lab-on-chip interferometry and process tomography (revealing an unknown quantum process with fewer measurements and fewer probe photons).

Experimental studies of collision processes, in which fundamental charged particles ionize simple atoms and molecules, provide the data necessary for our understanding of the many-body interaction and the development a theoretical description of this fundamental yet unsolved problem in collision dynamics. The ionization process plays an important role in astrophysical and technological plasmas and in the dissociation of molecules in the Earth's atmosphere. A comparison of single and multiple ionization of simple atomic and molecular targets by equi-velocity protons, electrons and their corresponding antiproton and positron antiparticles makes it possible to determine the effects of projectile mass and charge. The separation of 'pure' ionization from electron capture or transfer ionization processes can be studied in the special case of antiprotons colliding with light atoms. The absence of electron transfer is a significant simplification and the mass of the projectile enables straight-line trajectories models to be used.