Microwave and terahertz technologies play a critical role in modern life. Microwaves underpin mobile and satellite communications and are used for radar in navigation and meteorology. At higher frequencies, terahertz technologies are used to perform chemical sensing, non-invasive imaging, condition monitoring and more. These applications, and others, require fast detectors offering high sensitivity and the ability to perform spatially resolved imaging, which is particularly challenging in the terahertz domain where the majority of detectors require cryogenic cooling and offer slow thermal response times with limited absolute accuracy. In this proposal we seek to address this technology gap by developing a new class of atom-based sensors that exploit the extreme sensitivity of highly-excited Rydberg atoms which act as antennae to provide precision electric field measurement across the microwave and terahertz frequency range. Using lasers to excite Rydberg atoms in a thermal vapour cell, the radio-frequency fields can be measured from the resulting perturbation in the transmission of a weak probe beam. Atom-based sensors provide a number of advantages over traditional electric field measurement techniques; namely (i) they are intrinsically calibrated by relating the atomic properties to SI units to provide full measurement traceability, (2) act as point-like antenna for an in-situ measurement of the field, and (3) can be optically probed to enable sub-wavelength resolution of the radio-frequency field under study. The proposed research programme will explore a number of key challenges to implementing Rydberg-atom-based electric field sensors, including optimising the cell materials and geometry to minimise the perturbation or suppression of the applied field and developing measurement techniques to achieve the fundamental limits of sensitivity and accuracy. To address these challenges we will combine UK based expertise, including the pioneers of optical detection of Rydberg atoms, to fabricate and characterise atomic vapour cells compatible with microwave and terahertz measurements and demonstrate precision field measurement and 2D imaging of structured radio-frequency fields. To verify the device accuracy we will compare the performance of our sensors to state-of-the-art calibrated references at the National Physical Laboratory. Finally, we will demonstrate real-world application of the sensors to areas including all-optical microwave communication schemes similar to WiFi and characterisation of the complex near-field emission from a terahertz antenna array. These sensors offer a new approach to radiofrequency sensing, imaging and metrology and provide a route to achieving enhanced sensitivity at microwave frequencies whilst providing an enabling technology for emerging applications in the terahertz domain.

Over the last decade, solid-state lasers have been the subject of great interest with a wide range of applications thanks mostly to their superior output-power-to-wall-plug efficiency. However, the limited availability of colours (wavelengths) produced by these lasers forces the user to compromise by utilising a wavelength that is not ideal for the targeted application. Laser systems based on a nonlinear process, called Stimulated Raman Scattering, offer a simple solution to this need. However, the performance and usability of these so-called Raman lasers have traditionally been limited by thermal distortions inherent to the nonlinear process. This project will, for the first time, investigate the implementation of the adaptive control techniques - typically used in astronomy- inside Raman lasers to significantly alleviate this thermal issue. In this way, the behaviour and performance of the laser can be remotely controlled and optimised resulting in superior performance in terms of output power, beam quality and usability. This offers the prospect of several genuine breakthroughs including a range of world-firsts and world-records as well as the transfer of these laboratory-based systems into an engineering context. These significantly enhanced systems will address a wide range of applications including astronomy, environmental monitoring, cosmetics and medicine. For instance, the treatment of a variety of skin diseases such as psoriasis or port wine stain removal will strongly benefit from this project. Finally, knowledge transfer is an important feature of this project with a full strand of activity dedicated to it. The transfer of this technology will be performed within two high profile research groups at Macquarie University, Australia and at the University of Strathclyde. An industrial collaboration with M Squared Lasers will also take place, particularly targeting commercialisation of the final demonstrator.

Biophotonics describes a combination of biology or medicine and photonics, with photonics being the science and technology of generation, manipulation, and detection of light. Global Industry Analysts (San Jose, CA) forecast biophotonics markets to exceed $99 billion by the year 2018. Specifically, biophotonics methods are projected to outperform traditional diagnostic techniques, in part driven by the worldwide need for new innovations to address challenges in for example, healthcare, neuroscience, cancer biology and disease management. Additionally, there is an increasing space in optical analysis (e.g. spectrometers, analysers) which are required for a suite of applications more broadly in laser applications both in fields such as food, drink authentication and emergent areas using quantum technology. The international growth in photonics investment needs to be mirrored by a similar expansion of corresponding UK strengths at the University-Industry interface, which is at the heart of this EPSRC Prosperity Partnership. This grant brings together a partnership between EPSRC, The University of St Andrews and M Squared Lasers to address major research challenges that ultimately have business value and will add to quality of life, The innovative advances will include: 1) a new suite of imaging apparatus where we illuminate with a broad sheet of light rather than point by point scanning. This leads to faster image acquisition and lower sample exposure, thus leading to less "light" damage". Such imaging can lead to new insights for studies in neuroscience, diseases of the mind (dementia) and developmental biology. In turn this will shed light on numerous biological processes including the development of disease. Furthermore, the technology will be made high throughput so we can analyse multiple samples very quickly. They is relevant of the the pharmaceutical industry and drug discovery areas 2) We will look at light scattering (Raman) analysis which gives an optical readout of the chemical compassion of a sample. This will be developed in compact forms as well as with paper as medium to hold the sample. Studies will include use for anti-cancer drug monitoring, studies of infection and blood based disorders including sepsis. 3) we will use the ideas based around multiple laser interference - speckle - which is rich in information on the illuminating sources. This will herald step change for new forms of laser analysis of wavelength and even recording multiple wavelengths (spectra) from samples 4) we will look at new types of ultra compact microscopes that will be able to image below the diffraction limits, that is 100nm or smaller. these can be used in future in pathology to look at tissue biopsy (e.g. nephrotic disease) and ultimately displace other more expensive, time consuming approaches such as electron microscopy

For over a century, scientists have been fascinated, and at times mystified, by quantum mechanics, the theory that governs atoms, molecules and, indeed, all matter at a microscopic level. Central to this theory are two concepts: (1) Wave-particle duality - the idea that particles, such as electrons in an atom, can behave like waves and that light waves can behave like particles, and (2) entanglement - the concept that once two (or more) particles have interacted, they cannot be treated as independent entities no matter how far apart they are. These inherently quantum phenomena are at the heart of a wide range of physical effects, but their role is often extremely difficult to elucidate. For example, in solid materials, where every atom interacts with many other atoms, it is very challenging to predict and understand how the quantum behaviour will manifest itself, and yet it leads to effects, such as high-temperature superconductivity and special forms of magnetism. Our Programme will advance the understanding of these complex quantum systems by studying the behaviour of molecules cooled to very low temperatures where we can isolate their quantum behaviour. In this respect, the use of molecules is crucial. Their rich internal structure means they couple strongly to electric and microwave fields, and interact with each other over a much greater distance compared with atoms. In advancing our understanding of the quantum science of molecules, we will also learn how to harness their properties to build new devices, including sensors of exceptional sensitivity, computers capable of solving previously unsolvable problems, and simulators that can design new materials, magnets and superconductors. To study the quantum science of molecules in a controlled and systematic way, we need to develop the ability to manipulate the quantum properties of individual molecules. The first step towards this goal is to remove the thermal motion that normally hides their quantum behaviour. We have already developed methods to achieve this both using molecules in the solid state and in the gas-phase. In the solid state, we have demonstrated that certain organic dye molecules, when embedded in a suitable solid cooled to cryogenic temperatures, behave as near-ideal two-level quantum systems. Such molecules have the perfect properties to act as interfaces between quantum light and quantum matter - an essential building block of many future quantum devices. We will learn how to exploit these properties to generate single photons on demand, control individual photons, and store quantum information. In the gas phase, we have extended the methods of laser cooling and developed new techniques to cool molecules to within a millionth of a degree above absolute zero. In this quantum regime, it is possible to exert complete control over the internal state and motion of the molecules. With this control we can learn how to couple molecules to microwave and optical waveguides, to trap molecules on chips, to assemble ordered arrays of molecules that replicate the crystalline structure of real materials, and to explore how the interactions between molecules govern the behaviour of the many-particle system. These ambitious goals calls for radical advances, which we will deliver through a set of interconnected experiments intimately linked to state-of-the-art theory. With isolated molecules we will develop the control of single molecules and their coupling to single photons; with small arrays of interacting molecules we will control interactions and entanglement in simple geometries; and with two- and three-dimensional lattices we will understand the complex behaviour of strongly interacting many-particle systems. Through these projects, our Programme will lay the foundations for a broad range of future scientific advances and technological applications based on the quantum control of molecules.

Quantum mechanics provides a transformative approach to computing that is able to deliver computational performance surpassing the capability of modern digital hardware with as few as a hundred low-noise qubits. Quantum computers therefore offer a wide economic impact through access to disruptive new solutions to problems in both academia and industry, such as quantum chemistry for enhanced drug design or modelling of correlated media for designing new materials for aerospace and engineering. Quantum computation can also provide a dramatic speed-up of computationally expensive problems ranging from classical optimisation relevant to logistics (e.g. travelling salesman type problems) and financial services sectors or security and defence (e.g. factorisation). A major barrier to realising the benefits of quantum computation is developing a system with a large number of low-noise qubits. This Prosperity Partnership exploits a unique opportunity to combine the capabilities in advanced laser systems and quantum system integration of M Squared Lasers with the cold-atom and quantum algorithm expertise at the University of Strathclyde. Our vision is to develop SQuAre (Scalable Qubit Arrays) - a promising architecture for quantum computation and optimisation based on reconfigurable arrays of neutral atoms that is able to overcome the limitations in scaling of existing qubit architectures. This approach offers a highly competitive route to scalable quantum computation with large numbers of identical qubits capable of performing high-quality quantum gates, as demonstrated in recent experimental breakthroughs. Our Partnership combines the critical skills and knowledge that are integral to development of this new architecture. Together, we will - build a versatile platform for neutral atom quantum computing using scalable arrays of up to 100 qubits; - develop new algorithms and applications that solve industrially-relevant computation and optimisation problems through working directly with academic and industrial end-users; - create a software architecture to provide an accessible interface to programming the quantum hardware abstracted from the technical implementation; - perform characterisation and benchmarking of algorithms on our hardware to demonstrate a near-term practical advantage of quantum computation. The proposed research program will address important open questions relating to whether the quantum advantage for optimisation problems is preserved as the system scales, and how qubit imperfections affect the ability to obtain the ideal solutions. Early benefits of the Partnership will see development of new advanced laser systems and experiment control hardware that will establish the required supply chain technologies to underpin future scaling and commercialisation of the SQuAre platform to reach 1000 qubits within 10 years. This Prosperity Partnership has a strong foundation in the existing strategic relationship between M Squared Lasers and the University of Strathclyde with a track record in developing and commercialising novel quantum and photonics technologies. The Prosperity Partnership will transform our collaboration from globally competitive to internationally leading, placing the UK at the forefront of the rapidly growing field of neutral atom quantum computation in terms of academic leadership, validation of algorithms in real-life applications and commercial availability of quantum computing systems and components.