Final Report Summary - FQT (Frontiers in Quantum Technology)
The Innovative Doctoral Programme on Frontiers in Quantum Technology (www.imperial.ac.uk/fqt) aims to deliver an internationally competitive cohort of young researchers, equipped to be the research and industry leaders of the future, through interdisciplinary training at the frontiers of Quantum Technology. The most important output of this 4-year programme is to train 13 ESRs to complete their PhDs with outstanding research skills. We expected them to excel not only in research but in their ability to engage with both their peers and the general public. We combine the efforts of two distinct but closely linked areas of research to train young researchers: the generation of extreme light sources and the study of light-matter interactions, with a view to the development of quantum technology.
Training has included advanced courses in quantum technology and quantum information, complementary skills and an intensive outreach programme. The latter has included presentations to members of the general public at the 2014 annual Quantum Show and 2015 Science Festival as well as involvement in the science teachers’ workshop, all at Imperial College. A number of fellows have also visited local and international schools, giving talks on physics and their research.
The programme maintains close ties with industry, government labs and academic institutes across the UK, Germany, Austria, Italy and Japan. Fellows have spent up to 10 months on collaborative secondments to associate partner institutes. These have proved very successful, leading to publications in high impact journals as well as technology transfer projects, for example in setting up a long wavelength hollow fibre source at the ARTEMIS user facility at Rutherford Appleton Lab.
The programme also emphasises the development of a strong cohort mentality, through a variety of team building activities. In particular, our fellows have organised the Quantum Information, Computing and Control (QuICC) 2014 and 2015 summer schools, covering a series of intensive lecture courses given by internationally renowned senior researchers. Each summer school was attended by 50-60 students working on quantum technology from various parts of the world, and included a number of networking and social activities. Together with their supervisors, research fellows have also taken part in a one day programme meeting at the Royal Society, London, to give presentations, share ideas and to discuss their research progresses. This also gave them the opportunity to hear general talks on the university research portfolio and research translation to commerce by non-FQT Imperial College academics. The programme has also supported an international workshop, Quantum Optics to Quantum Technology (www.qotoqt.org) attended by more than 170 delegates, and providing an arena for fellows to showcase their work and participate in discussions.
Despite the initial period of fairly high intensity training the early stage researchers have made good progress with their projects. They have published nearly 40 papers in international journals and conference proceedings (and a number more under review), as well as contributed roughly 65 talks and posters at a variety of national and international conferences and research groups. Much of this work has proven extremely successful, resulting in world leading research published in a number of high impact journals, including Nature Physics, Nature Communications, Nano Letters and Physical Review Letters.
Some of the research highlights are as follows. Through their work, we have successfully trapped di-molecules and cooled them down to 50 millionth of a degree above absolute zero, breaking the world record of direct cooling of a molecule. At these temperatures, molecules can be used for high precision tests of fundamental physics or loaded into different trap geometries for quantum simulation. We have also been the first in the world to demonstrate the ground state cooling of the radial motional modes of trapped Calcium ions in a Penning trap. Currently, we have achieved this for a two-ion chain and up to 15 ions in a planar configuration.
Fellows have also been involved in the development of a table-top experimental apparatus capable of generating bursts of soft X-rays with durations only a billionth of a billionth of a second long. Such extreme pulses of light are essential in order to explore the role played by coherent electronic dynamics in mediating physical changes important to processes in chemistry, biology, and materials science, and we have been successful in producing fluxes nearly 100 times higher than previously reported by any other group in the world. This has allowed us to investigate the role played by electron and nuclear motion in mediating physical change in large organic polymers used in photovoltaic devices, and is an important first step to elucidating the role, if any, played by quantum coherence in the almost perfectly efficient energy transfer in photosynthesis.
We have also established ourselves as contenders in the world race for producing efficient single photon sources. These are crucial building blocks for a variety of quantum technologies, and are, for example, highly desirable for encoding, sending and processing quantum information. In recent years, one attractive realisation is offered through dye molecules, due to their high photostability and narrow emission lines. We have performed a detailed analysis of the optical properties of dibenzoterrylene, and successfully integrated single dye molecules with nano-photonic devices. These are hybrid plasmonic waveguides, designed to guide light and to enhance the interaction with a single emitter by a tight confinement of the waveguide mode. By depositing single molecules over the waveguides, we have witnessed the first coupling of the emitter to the nanophotonic structure.
A second promising approach is based on small bubbles of semiconductor material called quantum dots. These systems, however, suffer from noise due to magnetic interaction between the single electron that produces the photons and the many nuclei of the atoms in the material. We have developed two theoretical methods to understand this interaction and to manipulate the nuclei in such a way as to produce a good string of entangled single photons.
We have also developed a method to easily quantify how useful such a photon source is for building a quantum computer. In that way it is possible to compare different technologies and effectively work towards a functional system. Similarly, one of the most important tasks is the ability to certify whether a certain device is operating in a nonclassical manner, i.e. not explainable by 19th century Physics. We have developed a nonclassicality criteria for linear optical settings in which light emitted by multiple independent sources can interfere. In particular, this identifies a lower limit on the amount of intensity correlations obtainable in a classical regime, so that the observation of values smaller than this threshold acts as a “quantumness” signature.
We have also investigated the ultrastrong coupling of light to matter using the platform of superconducting circuits. Here one can study interactions between one (or many) artificial two-level atoms or qubits (represented by charge or flux circuits built according to certain specifications) with radiation fields (usually LC resonators). When the qubit-photon coupling dominates over the system’s bare energy scales a manifold of low-energy states with a high degree of entanglement emerges. We have proposed a feasible time-dependent scheme for extracting these quantum correlations and converting them into well-defined multipartite entangled states of non-interacting qubits. The protocol can be operated in a fast and robust manner, while still being consistent with experimental constraints on switching times and typical energy scales encountered in superconducting circuits.
Training has included advanced courses in quantum technology and quantum information, complementary skills and an intensive outreach programme. The latter has included presentations to members of the general public at the 2014 annual Quantum Show and 2015 Science Festival as well as involvement in the science teachers’ workshop, all at Imperial College. A number of fellows have also visited local and international schools, giving talks on physics and their research.
The programme maintains close ties with industry, government labs and academic institutes across the UK, Germany, Austria, Italy and Japan. Fellows have spent up to 10 months on collaborative secondments to associate partner institutes. These have proved very successful, leading to publications in high impact journals as well as technology transfer projects, for example in setting up a long wavelength hollow fibre source at the ARTEMIS user facility at Rutherford Appleton Lab.
The programme also emphasises the development of a strong cohort mentality, through a variety of team building activities. In particular, our fellows have organised the Quantum Information, Computing and Control (QuICC) 2014 and 2015 summer schools, covering a series of intensive lecture courses given by internationally renowned senior researchers. Each summer school was attended by 50-60 students working on quantum technology from various parts of the world, and included a number of networking and social activities. Together with their supervisors, research fellows have also taken part in a one day programme meeting at the Royal Society, London, to give presentations, share ideas and to discuss their research progresses. This also gave them the opportunity to hear general talks on the university research portfolio and research translation to commerce by non-FQT Imperial College academics. The programme has also supported an international workshop, Quantum Optics to Quantum Technology (www.qotoqt.org) attended by more than 170 delegates, and providing an arena for fellows to showcase their work and participate in discussions.
Despite the initial period of fairly high intensity training the early stage researchers have made good progress with their projects. They have published nearly 40 papers in international journals and conference proceedings (and a number more under review), as well as contributed roughly 65 talks and posters at a variety of national and international conferences and research groups. Much of this work has proven extremely successful, resulting in world leading research published in a number of high impact journals, including Nature Physics, Nature Communications, Nano Letters and Physical Review Letters.
Some of the research highlights are as follows. Through their work, we have successfully trapped di-molecules and cooled them down to 50 millionth of a degree above absolute zero, breaking the world record of direct cooling of a molecule. At these temperatures, molecules can be used for high precision tests of fundamental physics or loaded into different trap geometries for quantum simulation. We have also been the first in the world to demonstrate the ground state cooling of the radial motional modes of trapped Calcium ions in a Penning trap. Currently, we have achieved this for a two-ion chain and up to 15 ions in a planar configuration.
Fellows have also been involved in the development of a table-top experimental apparatus capable of generating bursts of soft X-rays with durations only a billionth of a billionth of a second long. Such extreme pulses of light are essential in order to explore the role played by coherent electronic dynamics in mediating physical changes important to processes in chemistry, biology, and materials science, and we have been successful in producing fluxes nearly 100 times higher than previously reported by any other group in the world. This has allowed us to investigate the role played by electron and nuclear motion in mediating physical change in large organic polymers used in photovoltaic devices, and is an important first step to elucidating the role, if any, played by quantum coherence in the almost perfectly efficient energy transfer in photosynthesis.
We have also established ourselves as contenders in the world race for producing efficient single photon sources. These are crucial building blocks for a variety of quantum technologies, and are, for example, highly desirable for encoding, sending and processing quantum information. In recent years, one attractive realisation is offered through dye molecules, due to their high photostability and narrow emission lines. We have performed a detailed analysis of the optical properties of dibenzoterrylene, and successfully integrated single dye molecules with nano-photonic devices. These are hybrid plasmonic waveguides, designed to guide light and to enhance the interaction with a single emitter by a tight confinement of the waveguide mode. By depositing single molecules over the waveguides, we have witnessed the first coupling of the emitter to the nanophotonic structure.
A second promising approach is based on small bubbles of semiconductor material called quantum dots. These systems, however, suffer from noise due to magnetic interaction between the single electron that produces the photons and the many nuclei of the atoms in the material. We have developed two theoretical methods to understand this interaction and to manipulate the nuclei in such a way as to produce a good string of entangled single photons.
We have also developed a method to easily quantify how useful such a photon source is for building a quantum computer. In that way it is possible to compare different technologies and effectively work towards a functional system. Similarly, one of the most important tasks is the ability to certify whether a certain device is operating in a nonclassical manner, i.e. not explainable by 19th century Physics. We have developed a nonclassicality criteria for linear optical settings in which light emitted by multiple independent sources can interfere. In particular, this identifies a lower limit on the amount of intensity correlations obtainable in a classical regime, so that the observation of values smaller than this threshold acts as a “quantumness” signature.
We have also investigated the ultrastrong coupling of light to matter using the platform of superconducting circuits. Here one can study interactions between one (or many) artificial two-level atoms or qubits (represented by charge or flux circuits built according to certain specifications) with radiation fields (usually LC resonators). When the qubit-photon coupling dominates over the system’s bare energy scales a manifold of low-energy states with a high degree of entanglement emerges. We have proposed a feasible time-dependent scheme for extracting these quantum correlations and converting them into well-defined multipartite entangled states of non-interacting qubits. The protocol can be operated in a fast and robust manner, while still being consistent with experimental constraints on switching times and typical energy scales encountered in superconducting circuits.