The terahertz (THz) region of the electromagnetic spectrum (radiation with frequencies around 10^12 Hertz) has traditionally been considered a difficult region to work in because it falls into a technology gap, with electronic, microwave sources at lower frequencies and photonic, infrared devices at higher frequencies. In recent decades, considerable efforts have been made to develop technologies that operate in the THz range in order to take advantage of the unique combination of properties exhibited by terahertz waves. For example, many everyday materials, such as plastics, paper, cloth etc. are transparent to THz waves, meaning that we can penetrate deeply into samples. However, unlike the more familiar X-rays, THz waves are safe to use because they are low energy and non-ionising. For this reason, terahertz imaging techniques are proposed for applications as broad as medical scanning, non-destructive testing, security, production line testing and medicine quality scanning. However, despite considerable efforts, terahertz cameras are still far slower and less sensitive than their optical counterparts and THz imaging applications are limited as a result. At Durham we have recently developed a novel approach to THz imaging that uses atomic vapour to convert difficult to detect terahertz waves into easy to detect optical frequencies. The atomic vapour is excited to high-lying (Rydberg) states using laser beams and once in these Rydberg states the atoms are very sensitive to perturbation by terahertz waves and emit optical light. This efficient THz to optical conversion process allows us to effectively capture terahertz images using standard optical cameras and observe frames rates exceeding 3000 frames per second, far exceeding the capabilities of other THz imaging techniques. This proposal intends to develop further our atom-based THz camera by using Quantum Cascade Lasers (QCLs) to provide the illumination. QCLs are semiconductor lasers capable of emitting high power in the terahertz frequency band - using QCLs will result in sharper spatial resolution and the ability to image larger areas and/or probe thicker samples in our imaging applications. In order to improve the image quality of our technique, we will also develop adaptive optics technology for the terahertz range. OA technologies are used extensively in the optical and infrared range to correct for aberrations in an imaging system. Previous attempts to perform AO in the THz range have been limited by the small range of movement of deformable mirrors and the slow image acquisition rates of THz cameras. We will develop large-stroke deformable mirrors to allow effective AO correction in the THz range. This will enable depth-selection in our THz imaging process and the removal of imaging artefacts and aberrations. Furthermore, we will add spectral (frequency dependent) functionality to out imager by adding a second atomic species (Rb87 + Cs133) thereby offering spectral sensitivity analogous to colour photography, expanding the capability of our THz imager to include material distinction by spectral response. Once we have constructed and characterised our QCL illuminated, AO corrected, 2-colour THz imager, we will apply it to a range of industrially relevant applications inspired and guided by our industrial project partners.

Vision: to drive and promote advances in optical biosensing capable of translation to low-cost monitoring, and to build a broad UK community in low-cost sensing for healthcare. Precision medicine tailors healthcare to individual patient characteristics. We are now entering a new era of precision health, which shifts towards healthy individuals, asking how we prevent disease with appropriate interventions, prolonging healthy lifespans. New challenges include the urgent need for precise technologies to monitor individuals throughout life, and for improved methods to interpret this wealth of data. Precision health demands new physical biosensors that are low-cost but elicit rich biochemical information and can be used outside the clinic. This frees up clinician-time and focusses scarce resources. It is vital to develop methods to extract/exploit downstream patient-specific information from the sensors. Current exemplars ('BioSensors 1.0') are wearable devices (such as Fitbit, Apple watch), which record only superficial parameters (eg. temperature, acceleration, blood oxygenation), while glucose/insulin sensors provide only very specific data; the major challenge of providing comprehensive analytical information with an affordable portable device remains key for healthcare. The SARS CoV-2 lateral flow tests popularised the notion of personalised disease testing and showed it can be a reality however they lack sensitivity, reliable and consistent interpretation, and robust reporting capabilities. The leading groups assembled here have a track record of pioneering optical approaches for new paradigms in the biosensing domain, from conception through to market. Together, they propose to synergistically explore the underpinning fundamental science of 'BioSensors 2.0' and develop key demonstrators that address clinical needs while building a broader UK community of academics, SMEs, institutes, & clinicians to drive this paradigm to real demonstrators. Current portable sensors are too simple and limited in their capability. Instead, we need to translate advanced lab-based technologies into portable devices. Systems aspects need care, while miniaturisation is challenging. Sensors should achieve multiplexing, use machine learning algorithms to interpret outcomes, auto-calibrate to ensure long term operation, survive changing conditions, and attain small-enough limits of detection required for various biofluids. This is a time-critical juncture, as other countries will start to develop in this space, though nothing explicitly exists yet- the NHS as the main UK provider may be a great driver. We also focus on community building, with targeted activities to ensure the UK is placed to capitalise on sensor developments. Through building a Big Idea 'Making Senses' for the Research Councils across the wider Sensors ecosystem, our team identified with EPSRC the lack of UK leadership and joined-up academia-industry-govt networks. Engaging with a wide range of stakeholders from SMEs to large entities (NPL, CPI, LGC, Turing..) and multinationals (P&G, AstraZeneca,..), we find strong appetite and market pull for new types of biosensors with application domains beyond the hospital, as well as industrial settings. New ways to leverage light-matter interactions (in which the is UK internationally strong) for realistic biodiagnostics demands a broad interdisciplinary research focus. This confluence aims to develop entirely new industries of the future, and to energise the UK interdisciplinary science base, which is vital over the next 50 years as we realise the new paradigm of BioSensors 2.0.

The Quantum Technology Hub in Sensors and Timing, a collaboration between 7 universities, NPL, BGS and industry, will bring disruptive new capability to real world applications with high economic and societal impact to the UK. The unique properties of QT sensors will enable radical innovations in Geophysics, Health Care, Timing Applications and Navigation. Our established industry partnerships bring a focus to our research work that enable sensors to be customised to the needs of each application. The total long term economic impact could amount to ~10% of GDP. Gravity sensors can see beneath the surface of the ground to identify buried structures that result in enormous cost to construction projects ranging from rail infrastructure, or sink holes, to brownfield site developments. Similarly they can identify oil resources and magma flows. To be of practical value, gravity sensors must be able to make rapid measurements in challenging environments. Operation from airborne platforms, such as drones, will greatly reduce the cost of deployment and bring inaccessible locations within reach. Mapping brain activity in patients with dementia or schizophrenia, particularly when they are able to move around and perform tasks which stimulate brain function, will help early diagnosis and speed the development of new treatments. Existing brain imaging systems are large and unwieldy; it is particularly difficult to use them with children where a better understanding of epilepsy or brain injury would be of enormous benefit. The systems we will develop will be used initially for patients moving freely in shielded rooms but will eventually be capable of operation in less specialised environments. A new generation of QT based magnetometers, manufactured in the UK, will enable these advances. Precision timing is essential to many systems that we take for granted, including communications and radar. Ultra-precise oscillators, in a field deployable package, will enable radar systems to identify small slow-moving targets such as drones which are currently difficult to detect, bringing greater safety to airports and other sensitive locations. Our world is highly dependent on precise navigation. Although originally developed for defence, our civil infrastructure is critically reliant on GNSS. The ability to fix one's location underground, underwater, inside buildings or when satellite signals are deliberately disrupted can be greatly enhanced using QT sensing. Making Inertial Navigation Systems more robust and using novel techniques such as gravity map matching will alleviate many of these problems. In order to achieve all this, we will drive advanced physics research aimed at small, low power operation and translate it into engineered packages to bring systems of unparalleled capability within the reach of practical applications. Applied research will bring out their ability to deliver huge societal and economic benefit. By continuing to work with a cohort of industry partners, we will help establish a complete ecosystem for QT exploitation, with global reach but firmly rooted in the UK. These goals can only be met by combining the expertise of scientists and engineers across a broad spectrum of capability. The ability to engineer devices that can be deployed in challenging environments requires contributions from physics electronic engineering and materials science. The design of systems that possess the necessary characteristics for specific applications requires understanding from civil and electronic engineering, neuroscience and a wide range of stakeholders in the supply chain. The outputs from a sensor is of little value without the ability to translate raw data into actionable information: data analysis and AI skills are needed here. The research activities of the hub are designed to connect and develop these skills in a coordinated fashion such that the impact on our economy is accelerated.