Sensors based on quantum technology have the potential to transform a number of scientific fields, including environmental sensing, geophysics, and ecology; biology and neuroscience; gravitational wave detection; and air, land, space, and sea-based navigation. One of the key players in quantum inertial sensing, that is, the sensing of acceleration and rotation, is that of atom-based sensing, which makes use of the fact that atoms, like light, can interfere with themselves. Just like one can use conventional matter-based optics to control light waves, one can use light-based optics to control these so-called matter waves, using the light fields generated by lasers to split, reflect, and recombine clouds of atoms. The advantage with these atomic systems is that atom-based rotation sensors can be up to ten billion times more sensitive than their light-based counterparts. The challenge now, for scientists, is to develop robust, scalable quantum sensors that are able to use as much of the massive potential sensitivity advantage as possible while being easily deployable in real-world scenarios. In this project, we are using shaken lattice interferometry (SLI), where ultracold atoms are trapped in a three-dimensional optical lattice. This optical lattice is the egg-carton-like potential produced when six lasers interfere with one another, two from each of the three dimensions. When the lattice potential is phase modulated (i.e., shaken), the trapped atoms, acting as matter waves, are made to split apart, move in a predetermined way, then come back together, after which an acceleration or rotation signal can be measured. While SLI is less mature than other atom interferometry techniques, it has the advantage that the atoms remain trapped throughout the interferometry sequence. In addition, the matter-wave optics of the shaken lattice interferometer can be modified to change the sensitivity of the interferometer to signals of differing magnitude and frequency. Additionally, SLI is easily scalable to a six-axis inertial sensor capable of measuring rotation and acceleration along all three dimensions. The goal of this work is to bring SLI to maturity. That is, in close collaboration with our industry partners, ColdQuanta, Inc, we will demonstrate a robust six-axis inertial sensor based on the concept of SLI with scaling and sensitivity on par with or better than the current state-of-the-art. In addition, we will work to understand the fundamental limits of this relatively new technology, as well as whether or not it can achieve sensitivity scaling and robustness that is better than any previous device. This will lay the foundation for the development of a practical, deployable, and scalable atom-based quantum inertial sensor that has the potential to revolutionise the field of navigation.

The 'trapped ion clock with enhanced reliability' project (TICKER) brings together world leading expertise in metrological-grade ion trap development, ultrastable room-temperature cavity-stabilised lasers, and laser source development to deliver unprecedented performance in a field-deployed state-of-the-art optical clock. Optical atomic clocks (OACs) have made extraordinary improvements over the last few decades and represent the pinnacle of precision measurement technology. The extreme accuracy of OACs enables exciting new opportunities for both fundamental physics and technology from detecting dark matter, relativistic geodesy, and improving satellite navigation accuracy. However, the science and technology impact from the current generation optical atomic clocks has been limited for the wider technology and industry base as they are fragile and complex laboratory-sized systems operated in well-controlled environments by skilled scientists. These limitations mean that only a handful of operational examples exist worldwide, restricted to National Metrology Institutes (NMIs) such as NPL. To unlock the transformative potential from OACs they must become simpler and more robust. This cannot be achieved by simply shrinking a laboratory clock; new approaches and technologies are called for. We will develop the technologies that bypass these constraints and allow the creation of practical optical clocks, focusing on the singly ionised strontium-88 (Sr+) system as the most viable candidate. Within this project we will develop metrological-grade ion traps that are manufacturable and robust enough to operate in less-well-controlled remote locations and mobile platforms, a transportable environmentally insensitive optical reference cavity, and a 422-nm DFB laser as a low-power and robust source for laser-cooling the ion. Atomic clocks based on trapped ions are inherently simpler and require lower power to operate than the other major class of high-performance clocks - neutral atom lattice clocks. Ion clocks also have relaxed requirements of the clock-laser, making them more suitable for noisy environments. Trapping and laser cooling a single ion requires less than a watt of RF power and less than a milliwatt of optical power; the electrode structure and vacuum system can be miniaturised and ruggedised using established techniques aided by finite element analysis. The Sr+ system is particularly attractive because the clock transition can be measured in a way that provides low sensitivity of the centre frequency to the environment. Additionally, the transitions in its simple energy level structure can mostly be addressed with commodity lasers. One exception is the 422-nm laser-cooling transition. Currently this light must be produced from either a vibration sensitive ECDL laser or inefficient frequency doubling from an infrared DFB laser. A 422-nm DFB laser would enable a great improvement in the SWAP and robustness. NPL's patented cubic cavity design is the leading transportable and force insensitive design and will be adapted to suit the requirements of field-deployable atomic clocks. Reducing the volume of the cubic cavity spacer from 125 cc to 27 cc still provides good frequency stability while greatly reducing the required environmental shielding. Moreover, we have invented a novel technique that exploits material anisotropy to further reduce environmental impact, which will extend the temperature-insensitivity alongside the force- and vibration-insensitive design. Together, with the addition of an optical frequency comb (being developed at pace under many other programs, to the requirements of optical clocks) we address the major challenges that are preventing optical clocks from field deployed applications.

Our overall goal is to develop an ultraprecision dicing / grinding system that will be applicable to photonics and microsystems. Working with a set of UK companies we will develop the system as a test-bed and implement a set of cutting edge instrumentation add-ons to better control the machining of materials with sub-nanometre surface finishes and sub-100 nanometre overall tolerancing on complex objects. Dicing relies on a diamond-impregnated cutting disc driven at up to 150,000 rpm on a spindle being accurately translated relative to a workpiece. Any vibration or lack of perfection in the system will result in degraded surfaces, chipping of diced facets and edge chipping on grooves and channels. Importantly when placing the dicing blade on the spindle, there are inevitable errors in truism, for example, whether the blade is accurately at 90 degrees to the spindle axis, whether the blade is perfectly concentric, and whether the translation is truly along the direction of the blade. Of course, in the real world, these things are never truly perfect, and so a goal of the project is to implement feedback and control, which allows adaptive compensation. In the project, we will build a system using 900kg of granite to hold and create an ultra-stiff system, then use air-bearing elements and control signals to identify and create feedback loops to achieve incredible levels of surface finish and overall precision. Critically we will work in the ductile machining regime where operation in the elastic limit of the material allows us to avoid brittle fracture and the sort of damage which majorly degrades the performance of optical and microsystem elements. We will be looking at a range of optical and electronic materials, including glasses, crystals and semiconductors. In the latter phase of the project, we will be looking to adopt and create new ways to 'true' the blade, using state-of-the-art metrology to control issues of blade side-wall wear, blade flutter, non-concentricity originated machining rates and load-related vibration. From this work, we expect to gain valuable insights that will help our commercial partners. Firstly, by creating new ultra-precision machine tools in the UK, secondly understanding how best to implement advanced techniques and thirdly, by making exemplar devices in technologically important materials to really prove our approaches work.

Quantum information science and technologies (QIST) are uniquely placed to disrupt and transform sectors across the board. Quantum technologies, by exploiting the distinctive phenomena of quantum physics, can perform functions fundamentally unachievable by technologies based solely upon classical physics. For example, when applied to computing, calculations and operations that would take the best supercomputers hundreds of years to complete could be resolved within seconds using quantum computers; as another example, QIST can also be used in sensing and imaging to obtain enhanced precision in a variety of measurements ranging from gas concentrations to gravitational waves, supporting established industries in sectors like manufacturing, energy and healthcare. Furthermore, the application of quantum technologies will have significant implications within communications and security given their ability to break traditional encryption methods used to protect data within financial transactions or military communications while at the same time offering a range of novel, secure solutions largely compatible with the existing infrastructures. The potential of quantum technologies is well demonstrated through its significant financial and strategic backing globally. Restricted to academic environments up until the start of the last decade, the worldwide investment into quantum initiatives has now reached $33 billion, with significant contributions made across China, the US, and Europe. In the UK, the strategic importance of quantum technologies is clear: with a strategic commitment of £2.5 billion over the next decade, EPSRC has listed Quantum Technologies a mission-inspired research priority and the Department for Science Innovation and Technology have named quantum technologies as one of their seven technology families within the UK's Innovation Strategy. It is clear that, around the world, quantum technologies are flourishing. While the technological potential and national importance of QIST to the UK is undeniable, a key challenge to realising our ambitions in this area is the ability to develop a quantum workforce of capable physicists, engineers, computer scientists, and mathematicians with both the requisite expertise in quantum information science and expertise in the technologies that will realise it. In addition, the leaders of the UK's quantum future must possess critical professional skills: they must be excellent communicators, leaders, entrepreneurs, and project managers. To meet this key ambition and its resultant needs, the programme offered by the Quantum Information Science and Technologies Centre for Doctoral Training (QIST CDT) is uniquely positioned to deliver the diversity of skills and experience needed to supply the UK with internationally renowned QIST leaders across policy, innovation, research, entrepreneurship, and science communication. QIST CDT students will receive academic training delivered by world-recognised top educators and researchers; undertake industrially-relevant training modules co-delivered with industry partners; gain hands-on experience within world-leading quantum research laboratories; receive one-to-one entrepreneurial mentorship; undergo intellectual property and science policy training; undertake on-site industry placements; and complete multi-faceted cohort projects designed to develop multidisciplinary teamwork. This combination of world-class academic research training, which can be undertaken in a vast array of quantum-technology-relevant sectors, with bespoke instruction in professional skills driven by the needs of current and future quantum industry, will produce graduates with a drive to make a difference in Quantum Technologies and the skills to make that happen.

Quantum sensing, imaging and timing will deliver transformative advancements across multiple sectors, including healthcare, infrastructure, transportation, environmental sustainability and security. These technologies make seeing the invisible possible: the inside workings of our brains, the infrastructure buried beneath our feet, the polluting gases in the air around us, the cancers lurking in our tissue or the drones in our crowded skies. These are some of the challenges we are poised to address. Our Hub in Quantum Sensing Imaging and Timing (QuSIT) brings together academic experts and industry partners, collaborating to translate cutting-edge research into tangible innovations. QuSIT will capitalise on a decade of substantial governmental and industrial investments, consolidating expertise and world-class capability from two established UK Hubs: QuantIC, specialising in quantum-enhanced imaging and the UK Sensing and Timing Hub. QuSIT will be a unified centre of excellence, providing thought leadership within the UK's quantum technology landscape, crucial to the National Quantum Strategy. At the heart of QuSIT is a world-leading and diverse team of 45 investigators, comprising both emerging talents and seasoned experts. Their impressive academic track record is complemented by a shared commitment to translating innovation from the laboratory to address real-world challenges. Our researchers have a history of licensing technology to industry and launching their own ventures. The technologies we will exploit are based on both atomic states and entangled photons to create quantum devices that sense and image otherwise invisible optical wavelengths, radio-frequencies, magnetic and gravitational fields, and exploit precision time, including: Optical wavelength translation using non-linear interferometry and non-linear optics Atom interferometry for gravity and gravity gradient sensing Waveguide optics for wavelength conversion Optically pumped magnetometers for zero and high absolute fields Metasurfaces for lightweight and compact optics Wavefront shaping for seeing through obscuration Data fusion of quantum and classical sensor data, using AI and Bayesian Inference Quantum enabled frequency sources to enhance radar systems Our approach revolves around co-creating research with end-users, fostering collaborations between academics and industry players throughout the supply chain, and rigorously testing and refining our innovations through field trials in partnership with our collaborating companies, pursuing new approaches to: Line-of-sight imaging of polluting, or toxic gases and chemicals Monitoring of brain health Screening for concealed and dangerous objects Imaging of underground infrastructure Mid-infrared, holographic microscopes for clinical diagnosis Application of precise timing for the monitoring of congested airspace The hub is supported by companies and other end-users many of which have made significant investments. These include BT, BAE Systems, Department for Transport, Great Ormond Street Hospital, National Grid, National Physical Laboratory, Ordnance Survey and Severn Trent Water. In the increasingly competitive international landscape, QuSIT will provide the vision and have the convening power required to ensure that the UK remains at the forefront of quantum technology internationally, delivering accelerated economic growth and societal benefits through collaboration between academia and industry.