Final Report Summary - QTEA (Quantum sensor technologies and applications) The ITN QTea project (www.itnqtea.eu) was aimed at preparing a cohort of (mostly) early-stage researchers for the emerging challenges in quantum technology development and applications across all sectors, i.e. from academic environments to industrial device fabrication. The scientific scope of the network focused on the physics of modern quantum sensors based on precision measurements of inertial forces, electro- magnetic fields, and time and frequency. Our collaboration of various partners from academia and industry helped young researchers to gain knowledge and experience across the value chain. On the fundamental side, important ideas and major contributions to current research in this field have originated from atomic physics and quantum optics. Highly sensitive measurements can be performed using various types of optical as well as matter wave interferometry. QTea therefore has put an emphasis on these research areas. Working towards real world applications, our industrial partners contributed valuable experience ranging from device engineering to geological surveys for the oil and gas industry.The project objectives were:• Providing individual research training for the fellows, complemented by an overarching training programme at the consortium level.• Establishing close scientific collaboration between academic and private sector industrial researchers.• Ensuring effective knowledge transfer between all partners of the network. This is in particular important at the industry-academic connection points where commercially developed equipment enables experiments and quantum sensing technology, or when operational sensor technology is to be brought to industrial applications.The specific scientific objectives were to explore concepts, develop technologies and enable or improve applications in the areas of:• Atomic and molecular precision spectroscopy and clocks.• Inertial force measurements, with a focus on gravitational fields and rotation.• Development of a new generation of magnetic sensors based on ultra-cold atoms and their interaction with complex semiconductor and metal structures.The key components of the training programme are broken down into three main categories:• Exploration of novel concepts with the aim of establishing new techniques for sensors and metrology applications based on ultracold gases and quantum optics.• Development of technology with a direct view towards applications where we will steer most recent proof-of-principle laboratory demonstration experiments in the direction of applications, ranging from fundamental science metrology to commercial devices.• Usage of actual sensors in various applications with a focus on feasibility, practicalities, managerial, societal, and entrepreneurial aspects as well as actual measurements and improvement of their performance.Our consortium recruited a cohort of 12 Early Stage Researchers and 3 Experienced Researchers. During the first two years, the fellows were introduced to their individual research projects and were provided with individual training. During the second stage, the fellows took ownership of their individual projects, developed expert knowledge and skills and established their role within their local research teams. At the outset of the project, the fellows were introduced to the nature of the network, its structure, roles, and communication channels as well as networking and secondment opportunities. Arrangements for joined supervision were made and a fellow-centred buddy system was established. Over the course of the four year programme, our consortium organised ten network-wide training events to provide further scientific and technological training to the cohort. QTea co-organised an international summer school on foundations and applications of “Quantum Matter” in Granada, Spain. A technology workshop for the fellows on fibre technology, spectroscopy, and metrology was held in Copenhagen by our partners NKT Photonics and the Danish National Metrology Institute DFM. A four-week extensive "training camp" was organised in Nottingham, UK, with external expert lectures on quantum optics, optical clocks, magnetometry and nuclear magnetic resonance as well as specialised lectures on their research projects provided by fellows to their peers. The programme was complemented by complementary skills training and technical workshops. A summer school on matterwave optics was organised in Enagron by our project partner Institute of Electronic Structure and Laser in Crete. The school prepared our fellows to take part in the following international conference on "Frontiers in Matter Wave Optics" in Chania, Crete. During the second half of the QTea project our fellows had grown into their roles not only as researchers but developed organisational and networking skills. The fellows organised a student led summer school at the University of Hamburg, Germany, which included a workshop on Intellectual Property. A final event was organised at the University of Birmingham, UK, in the context of a quantum technology conference, linked to the UK National Quantum Technologies Programme. On the level of individual host institutions, each fellow was trained through specific scientific projects that are designed to lead to PhD qualification. Locally, a range of training courses was offered, from language skills to targeted scientific courses. Over the course of the QTea programme, our fellows had ample opportunity to make international contacts and gain complementary knowledge and skills through secondments to full and associate partners of our network. The results from this research have been disseminated through a large number of peer-reviewed publications and numerous contributions to international conferences. Some developments have led to patent applications that are under review.The most important outcomes of the QTea project are not only the achievements in research and development. Our fellows could use our programme as a pivotal stepping stone for their further careers. Some stayed in academia, continuing their PhD degrees or being hired as postdoctoral researchers. Other fellows now pursue an industrial career. These opportunities arose at partner institutions within our network but also at high-profile institutions from outside our network. We are proud of this success that our fellows have demonstrated.