The CPW-cavity planar Penning trap. Circuit-QED with trapped electrons and planar superconducting microwave cavities in a chip.

This research project focuses on the development and experimental demonstration of a novel superconducting planar Penning trap for electrons, which is conceived to become a versatile building block of future quantum circuits. The proposed new technology is capable of next generation high precision measurements of fundamental constants (such as the g-factor of the free electron and the fine-structure constant) using advanced quantum metrology protocols, as proposed by Cirac and Gabrielse from MPQ/Garching and Harvard, respectively. It is also conceived for the development of a new ultra-high precision magnetic microscope, using a single trapped electron as magnetic sensor. The envisaged magnetic microscope will permit the detection, with unprecedented accuracy and spatial resolution, of local magnetic fields on surfaces. The third pillar of the proposed new trapping technology is the implementation of matter-wave interferometric tools for trapped electrons. Although electrons were used many decades ago in the first experimental observations of wave-particle dualism, such a basic tool as a coherent beam-splitter has never been implemented in Penning trap experiments. Our research will try to fill this important gap. The motivation is the study of systems of correlated and entangled trapped electrons, thereby taking advantage of the extraordinary control offered by well-proven Penning trap techniques over the precise preparation of the trapped particles, their quantum numbers and spin orientations.Penning traps are used in a wide variety of applications including: mass spectrometry, high precision measurements of atomic and nuclear properties, antihydrogen production, plasma physics and others. The maturity achieved by Penning trap technology has recently led to several theoretical proposals about the construction of a quantum processor using trapped electrons. Novel scalable planar Penning traps have been conceived and actually built. However, the initial planar traps for electrons are limited in their experimental capabilities, since they cannot include some tools of conventional 3D Penning traps essential for the good performance of those. We propose a new Penning trap technology, which overcomes those limitations. Moreover, its novel design is also highly inspired by the extraordinary development of planar microwave technology. Superconducting microwave resonators with extremely low losses have been built on a chip, capable of storing a single photon for a long time, which, among others, permits the coherent transfer of quantum information between different physical systems in the chip. A very prominent experimental demonstration of the capabilities of such resonators has been achieved by the group of Prof R Schoelkopf from the University of Yale (USA). The mentioned microwave planar cavities (or resonators) offer plenty of new possibilities for trapped electrons and indeed constitute the main technological basis of the new CPW-cavity Penning trap to be developed within this project.

The CPW-cavity Penning trap project addresses scientific issues that are at the technological forefront of development in the field of planar Penning traps for applications in circuit-QED, matter-wave interferometry with electrons, quantum metrology and high precision measurement of fundamental constants. The project is of direct interest to a very wide audience, including scientists working with electrons and ions for quantum computation and high precision measurements and also for those working with ultracold atoms in atom chips and superconducting quantum circuits. The proposed new trap and the planned quantum interferometric instruments for electrons might become a very useful tool, exportable to plenty of already existing experiments in the UK and in other countries. A direct practical consequence of this wide academic relevance are the existing offers for long-term scientific cooperation with other Universities and research institutions in the UK and overseas. In particular, within this project direct cooperation with the University of Southampton and its Nanofabrication centre will be essential: the superconducting CPW-cavity traps will be fabricated at that mentioned facility, with the invaluable support of Professor Michael Kraft. The main economic and social impact of the research project will be immediate and will arrive in the form of training of young British students. Working at a high level and with the aim of achieving excellence in such a competitive environment like the avant-garde research in quantum technologies is a unique opportunity for any young scientist. The technical skills to be developed by the SEPnet PhD and Sussex students include: microwave planar technology, chip nanofabrication, ultralow noise electronics, matter-wave interferometry, expertise in advanced engineering and scientific software (COMSOL, SimIon, Mathematica, AutoCad) and some others. The wealth of a modern nation as the UK is based upon its most important natural resource, that is: its own people and its ability to attract the most privileged brains from overseas. In that sense, completing a PhD in the very demanding area where this project is located will deliver a young and highly motivated professional, ready to compete in academia or in industry at the highest level, hence enabling British universities or British companies to be among the leaders in the world. The PI has been awarded recently a Marie Curie Reintegration grant funded with 15 kEuro / year for the next three years (starting May 2010) which, among others, specifically aims at building long-term cooperation with other European countries. Particularly helpful, both for the good progress of the planned experiments and the dissemination of the results, will be the privileged access to Prof J Schmiedmayer in Vienna (former supervisor of the PI) who heads one of the leading groups in the area of atom chip technology. The excellent connections to the theory groups at the University of Innsbruck (specially Prof H Ritsch), one of the main centres for research on quantum computation in Europe, will also be intensified. The MC Reintegration grant provides funding both for visiting those countries as well as for inviting top scientists to visit our lab at the University of Sussex. The first visit to Vienna is planned for the middle of July 2010, where more concrete details of the cooperation will be discussed. Another very important scientific partner is Prof K Blaum from the Max Planck Institute for nuclear Physics in Heidelberg. Mr Blaum is an internationally recognised expert in mass spectrometry and Penning trap technology. An invitation for scientific discussion has been already received and a first visit to Heidelberg is planned for June 2010. Thanks to the MC Grant further collaborations will be explored, with the groups of Prof P Tombesi in Camerino (Italy), Prof G Gabrielse in Harvard, Prof F Schmidt-Kahler in Ulm and Dr P Treutlein in MPQ/Garching.