The unique way that light interacts with magnetic/non-magnetic metal ultra-thin films with thicknesses less than 1/5000th the width of a human hair has recently been shown to offer a route to producing novel sources of radiation with wavelengths that cover a wide range stretching from the mid- to far- infrared. This emission covers the THz region that lies between the microwave and the infra-red wavelengths of the electromagnetic spectrum; a wavelength range that remains difficult to cover, but has an enormous potential for a diverse range of applications. For example, THz radiation is particularly useful for security screening of people at airports due to its non-ionising properties, as well as for looking at the spectral fingerprints of materials including explosives, drugs and dust particles. The atomic properties of interfaces are well known to be critical to the functionality of many technologically important devices, examples include spin-torque transfer magnetic random-access memory (STT-MRAM), the sensors and media used in hard disk drives and new, artificial multiferroics. This project is focused on developing much needed understanding of how the emission process from ultra-thin magnetic structures depends on the material properties. By gaining understanding of how the underlying mechanisms are responsible for the emission process we will be able to demonstrate commercially-viable emitters. More specifically, the first emitters will be realised that operate without the need for an external magnetic field, overcoming the limitation this requirement currently imposes on the active emitting area and output energy. THz radiation also provides a currently untapped approach to investigating spin-based devices. The knowledge gained in understanding the relationship between material properties and THz emission will prove invaluable in the design of spintronic devices being developed for the next generation of data storage devices. The overall goal is the development of sources of THz radiation that will have impact in a number of future application areas, in particular when looking at the spectral fingerprints of materials for detecting dangerous gases and dust particles which present serious health and safety concerns in areas such as the mining industry. Hence, the development of well-understood spin-based emitters would have a direct impact on UK economic success by enabling the development of new applications of THz radiation and spin-based devices that will add to the technological advancement of society.

Informed by the requirements of future precision atomic clocks, this project targets the development of an "optical frequency comb" -- a laser providing a thousands of regularly spaced optical frequencies which form a ruler in frequency that is a critical component in quantum timekeeping devices. Quantum technology research in the UK and internationally is developing small atomic clocks to which the frequency of a special laser (not a laser comb) can be locked with extremely high stability. Yet these clocks "tick too fast": the clock laser oscillates at about 500 trillion "ticks per second", far too quickly to allow it to be interfaced to real-world systems like computer networks and electronic navigation devices. The laser comb can be used like a gearwheel to reduce this rate to one more appropriate for everyday applications of about 10 billion ticks per second. In this sense the comb works exactly like the clockwork mechanism in a pendulum clock, reducing the faster ticks of the pendulum to less frequent increments in the positions of the minute and hour hands. To date, practical laser combs with the right technical characteristics have been difficult to produce, even with lab-scale dimensions. This project will address the need for compact combs as sub-systems within a practical optical clock--and the current absence of such technology--by developing a disruptive laser-comb architecture. This will be compatible with visible clock transitions in new ion-based time standards, and will have a scale suitable for integrating into quantum timekeeping devices needed by sectors from security, energy, geodesy, finance and defence. Our approach will leverage advances in ultrafast lasers and integrated nonlinear photonic devices, complementary technologies in which the investigators at Heriot-Watt and Glasgow Universities are world leaders. Areas of emphasis are the development of robustly packaged infrared pulsed lasers operating at around 10 GHz (10 billion "ticks per second"), and the efficient extension of these to the visible region by using chip-scale "super-continuum" devices prototyped in the material gallium arsenide and finally to be made from the material silicon nitride. The output of these lasers will be made into a frequency comb by using a combination of optical and electronic stabilization techniques. The project will be developed in close association with several academic and industrial partners who will contribute resources and expertise in lasers (Laser Quantum Ltd.), optoelectronic manufacturing (Optocap Ltd.), optical frequency metrology (NPL), optical frequency standards (EPSRC UK Quantum Technology Hub in Sensors and Metrology), optical systems engineering (Fraunhofer Centre for Applied Photonics) and expertise in end-user applications of combs (Dstl). Our partners have committed up to £527.5K cash and £182K in-kind support, and span the supply chain from devices and systems, to verification and end-users. This breadth and depth of commitment will ensure that the project gains real-world traction and will have an enduring impact. The modular comb targeted by the project resonates strongly with EPSRC's Photonics for Future Systems priority and addresses key portfolio areas of Optical Devices & Subsystems, Optoelectronic Devices & Circuits, Quantum Devices, Components & Systems and RF & Microwave Devices. By the end of the project we expect to have demonstrated and evaluated this novel laser-comb technology, as well as created considerable new knowledge and IP in the areas of ultrafast lasers and integrated nonlinear photonics. This will leave us in a strong position to translate the technology into systems of commercial and scientific benefit to our industrial and academic partners and wider society.

The astronomy community faces a critical problem in how to provide perpetual online calibration of new ultra-high-resolution spectrographs, which play a central role in answering today's "big questions" such as the discovery of extra-solar Earth-like planets, and the variation of "fundamental" constants. Since around 2007, the photonics community has been working with astronomers to provide a solution, in the form of an ultra-stable laser calibration source producing a "comb" of thousands of regularly spaced optical frequencies. Techniques pioneered by Nobel laureates Hall and Haensch showed how such a comb could be stabilised, allowing the constituent comb lines to be frozen in frequency to precisions approaching one part in 1,000,000,000,000,000,000 (actually a level rather more accurate than is needed in many astronomy contexts). HIRES and ESPRESSO are proposed high-resolution spectrographs at the E-ELT and VLT, respectively, whose underpinning science cases include the search for Earth-like exo-planets, primordial nucleosynthesis and the possible variation of fundamental constants. Both instruments demand exceptional radial velocity accuracy and stability, (up to 2 cm/s for HIRES), which can only be realized by embedding perpetual online calibration in the form of a broadband laser frequency comb. No laser frequency comb technology fully offering the necessary wavelength coverage and mode spacing has yet been demonstrated. Furthermore, the current techniques used to obtain the necessary wavelength coverage and mode spacings introduce artifacts which corrupt the calibration results when deployed on a spectrograph. Consequently research is needed to explore the feasibility of alternative laser frequency comb concepts which could meet the needs of the ESPRESSO and HIRES projects. Building on unique laser frequency comb expertise at HWU, and working with stakeholders in the HIRES and ESPRESSO instruments, this project will evaluate several new concepts for broadband laser frequency comb architectures based around optical parametric oscillators, and addressing the essential calibration-source criteria for stability, uniformity, accuracy and comb-line spacing. Engagement in the project by our principal industrial partner, Laser Quantum Ltd., will support the project with Ti:sapphire pump lasers of high repetition rate, and with vital technical know-how. A further exploitation route is provided via the new Heriot-Watt spin out company Chromacity Ltd., formed to commercialise Heriot-Watt's femtosecond OPO technology. Outcomes from the project will take the form of a technical assessment summarizing the suitability of the candidate comb architectures, and a demonstrator of the most promising system.

Recently, an influential American business magazine, Forbes, chose Quantum Engineering as one of its top 10 majors (degree programmes) for 2022. According to Forbes magazine (September 2012): "a need is going to arise for specialists capable of taking advantage of quantum mechanical effects in electronics and other products." We propose to renew the CDT in Controlled Quantum Dynamics (CQD) to continue its success in training students to develop quantum technologies in a collaborative manner between experiment and theory and across disciplines. With the ever growing demand for compactness, controllability and accuracy, the size of opto-electronic devices in particular, and electronic devices in general, is approaching the realm where only fully quantum mechanical theory can explain the fluctuations in (and limitations of) these devices. Pushing the frontiers of the 'very small' and 'very fast' looks set to bring about a revolution in our understanding of many fundamental processes in e.g. physics, chemistry and even biology with widespread applications. Although the fundamental basis of quantum theory remains intact, more recent theoretical and experimental developments have led researchers to use the laws of quantum mechanics in new and exciting ways - allowing the manipulation of matter on the atomic scale for hitherto undreamt of applications. This field not only holds the promise of addressing the issue of quantum fluctuations but of turning the quantum behaviour of nano- structures to our advantage. Indeed, the continued development of high-technology is crucial and we are convinced that our proposed CDT can play an important role. When a new field emerges a key challenge in meeting the current and future demands of industry is appropriate training, which is what we propose to achieve in this CDT. The UK plays a leading role in the theory and experimental development of CQD and Imperial College is a centre of excellence within this context. The team involved in the proposed CDT covers a wide range of key activities from theory to experiment. Collectively we have an outstanding track record in research, training of postgraduate students and teaching. The aim of the proposed CDT is to provide a coherent training environment bringing together PhD students from a wide variety of backgrounds and giving them an appreciation of experiment and theory of related fields under the umbrella of CQD. Students graduating from our programme will subsequently find themselves in high-demand both by industry and academia. The proposed CDT addresses the EPSRC strategic area 'Quantum Information Processing and Quantum Optics" and one of the priority areas of the CDT call, "Towards Quantum Technologies". The excellence of our doctoral training has been recognised by the award of a highly competitive EU Innovative Doctoral Programme (IDP) in Frontiers of Quantum Technology, which will start in October 2013 running for four years with the budget around 3.8 million euros. The new CDT will closely work with the IDP to maximise synergy. It is clear that other high-profile activities within the general area of CQD are being undertaken in a range of other UK universities and within Imperial College. A key aim of our DTC is inclusivity. We operate a model whereby academics from outside of Imperial College can act as co-supervisors for PhD students on collaborative projects whereby the student spends part of the PhD at the partner institution whilst remaining closely tied to Imperial College and the student cohort. Many of the CDT activities including lectures and summer schools will be open to other PhD students within the UK. Outreach and transferable skills courses will be emphasised to provide a set of outreach classes and to organise various outreach activities including the CDT in CQD Quantum Show to the general public and CDT Festivals and to participate in Imperial's Science Festivals.

Modern manufacturing has been revolutionised by photonics. Lasers are central to this revolution, as they continue to transform the fast-changing manufacturing landscape. Photonics manufacturing represents an industry worth £10.5bn per annum to the UK economy, growing at about 8.5% annually and directly employing more than 70,000 people. UK Photonics exports are currently the 4th largest by value of any UK manufacturing sector, following automotive, aerospace and machinery exports. More importantly, UK Photonics exports more than 75% of its output relative to the UK manufacturing average of only 34%. Laser technology in particular underpins a number of leading UK industries in the aerospace, automotive, electronics, pharmaceuticals and healthcare engineering sectors. Over four decades, the Optoelectronics Research Centre at the University of Southampton has maintained a position at the forefront of photonics research. Its long and well-established track record in fibres, lasers, waveguides, devices, and optoelectronic materials has fostered innovation, enterprise, and cross-boundary multi-disciplinary activities. Advanced fibres and laser sub-systems, manufactured in Southampton by companies spun-out from the Optoelectronics Research Centre, are exported worldwide. Working closely with UK photonics industry, our interconnected and highly synergetic group will optimally combine different laser technologies into hybrid platforms for miniaturised, efficient, low-cost, agile and reconfigurable smart laser systems with software-driven performance. This is only possible because of the controllable, stable and robust, all-solid state nature of guided-wave lasers. A smart laser looks like its electronic equivalent - a single small sealed maintenance-free enclosure with a fully controlled output that is responsive to changes in the workpiece. The laser knows what material it is processing, how the process is developing and when it is finished. It is able to adapt to changes in the materials, their shape, reflectivity, thickness and orientation. This leads to new tools that enable innovative manufacturing processes that are critical in increasing competitiveness in important manufacturing sectors. Finally, the advanced laser technologies developed within this platform are expected to have a wider impact outside the manufacturing arena, in areas such as sensing, healthcare, and the medical sectors, as well as homeland security helping to establish an important laser sovereign capability.