Non-equilibrium Dynamics of Quantum Open Systems: From Fundamental Theory to Applications in Cold Atoms, Superconducting Circuits and Quantum Glasses

Lead Research Organisation: University of Nottingham
Department Name: Sch of Physics & Astronomy

Abstract

The last twenty years have seen a revolution in the experimental realisation of quantum systems. Ultra-cold atomic gases are routinely created in the laboratory and used for the study of complex many body phenomena. Experimental advances have also allowed an unprecedented degree of control at the level of single quantum degrees of freedom, such as in trapped ions, quantum dots, and nano-electromechanical systems. These developments are not only of fundamental importance, but also promise exciting technological applications as varied as quantum computing and precise measurement devices.Real quantum systems are open which means that they interact with their surrounding environment. This leads to an irreversible loss of coherence or quantumness . Most of the practical and conceptual questions in quantum dynamics today are related directly or indirectly to the problem of maintaining quantum coherence. Furthermore, open quantum systems are intrinsically systems not in equilibrium. But while there has been much recent progress in our understanding of classical (i.e. non-quantum) systems out-of-equilibrium, much less is understood about the analogous quantum problem. The proposed research will produce a step-change in our understanding of the non-equilibrium dynamics of open quantum systems.Our proposal has two general aims. The first one is to bridge the gap in understanding that exists between classical and quantum non-equilibrium systems, by applying and adapting the most novel methods, concepts and techniques from statistical non-equilibrium physics to open quantum systems. Many of the recent advances in classical non-equilibrium science have originated from the study of complex ``soft'' condensed-matter systems such as glasses. The new set of ideas and techniques that this has spawned has not yet been fully exploited in the quantum realm. This proposal will bridge this gap. The outcomes will be two-fold: a new general methodology and set of concepts for studying complex quantum systems far from equilibrium; and new predictions and insights for specific systems of current interest, such as cold atoms and quantum superconducting circuits, including novel experimental proposals. The second general aim is to design and perform innovative experiments on ultracold atomic systems that uncover unexpected dynamical phase transitions and other dynamical fluctuation behaviour by employing novel high sensitivity and temporal resolution detectors. The experiments will be based on ultracold thermal and quantum degenerate gases (Bose-Einstein condensates) in highly controlled dynamic microengineered environments of varying dimensionality near atom chips. This proposal is about a multi-pronged approach to the current issue of quantum non-equilibrium. It aims to establish a novel conceptual framework, both at the theoretical and experimental level, to address this problem. It will deliver a range of new theoretical, computational and experimental methodologies and techniques for the characterisation of open quantum systems. The more ambitious goal is the discovery of dynamical phase transitions in quantum non-equilibrium matter, with the potential to change the way we think about non-equilibrium phenomena.

Planned Impact

The primary focus of this research programme is to advance understanding of quantum matter far from equilibrium at a fundamental level. Non-equilibrium is one of the central problems of current physical sciences and engineering, as recognised by EPSRC in its Matter far from equilibrium signpost, and by DOE as one of its Grand Challenges: Characterize and control matter away from equilibrium . Our proposal is about fundamental understanding of non-equilibrium in the quantum world, and will impact in the following: - Knowledge generation and dissemination. We will continue to disseminate our results to the widest scientific audience by publishing in leading journals, preprint servers and websites. Presentation of our results at a broad range of international conferences will maximise the impact of our work to researchers in different disciplines. For outstanding research results press releases will be issued by the University's Communications Office which liaises with the national media. The applicants have experience in dealing with general public science media and newspapers. - Personnel training. The research described in this proposal will provide an excellent opportunity for the PhD student and PDRAs employed to develop their careers. The theory PDRA will work closely with the theory applicants learning a variety of analytical and numerical techniques as well having the opportunity to collaborate with the experimental CI. The experimental PDRA will acquire and refine skills in diverse areas ranging from state-of-the-art microfabrication to operating high-tech laser devices and complex computer modeling. Beyond the School of Physics & Astronomy, the PDRAs and PhD student will be able to participate in all activities of the Midlands Physics Alliance Graduate School. PDRAs and students working with the PI and CIs have found it easy to move into employment in the industrial and other sectors including high-tech, teaching, finance, medical physics, and geophysics, and in faculty jobs in academia. We will also host and train undergraduate research students, by means of full-time summer placements in our groups, providing motivated undergraduates with a significant advantage for their career prospects, either in industry or research. - Public engagement. We will actively promote interest in our work well beyond the academic community. The applicants together have a track record of attracting popular media interest with articles appearing in publications such as the New York Times, New Scientist, Physics Today. We will also promote interest in our work and in science in general amongst the public by postings on the School of Physics & Astronomy website. The applicants and PDRAs will actively participate in the outreach activities organised by Nottingham Physics & Astronomy: regular Open Days for school pupils, the sixth-form conference Exploring Physics, and lecture visits to schools. A very successful initiative is the Sixty Symbols project of short films aimed at explaining physics to the general public, which have attracted more than a million viewers from all continents. The applicants will continue to participate actively in this effort. - Intellectual property and knowledge transfer to industry. Much of the technology that will be developed as part of the experimental programme will be an ingredient for quantum technology applications. The light-sheet atom detector will significantly enhance sensitivity of cold atom based sensors of magnetic, electric and gravitational fields. In superconducting circuits an aim is to determine whether an artificial atom coupled to a superconducting stripline could be used as a bifurcation amplifier, with potential applications in quantum computing technology. To exploit emerging knowledge transfer, interaction with industry and IP exploitation we will coordinate with the School's Business Development Executive.

Publications

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Description The last twenty years have seen a revolution in the experimental realisation of quantum systems. These developments are not only of fundamental importance, but also promise exciting technological applications as varied as quantum computing and enhanced measurement devices. Real quantum systems are "open" which means that they interact with their surrounding environment. Moreover, open quantum systems are intrinsically systems not in equilibrium.
Our proposal had two general aims. The first one was to bridge the gap in understanding that existed between classical and quantum non-equilibrium systems, by applying and adapting the most novel methods, concepts and techniques from statistical non-equilibrium physics to open quantum systems. The outcomes associated to this aim are a new general methodology and set of concepts for studying complex quantum systems far from equilibrium; and new predictions and insights for specific systems of current interest, such as cold atoms and quantum superconducting circuits, including novel experimental proposals. The second general aim was to design and perform innovative experiments on ultracold atomic systems that uncover unexpected dynamical behaviour by employing novel high sensitivity and temporal resolution detectors. The experiments will be based on ultracold thermal and quantum degenerate gases (Bose-Einstein condensates) in highly controllable dynamic microengineered environments of varying dimensionality near atom chips.
Exploitation Route On the theoretical side we have laid the foundations for several new avenues of research into quantum non-equilibrium. This has led for example to the award of a new EPSRC grant on Rydberg Soft Matte between Nottingham theorists and Durham experimentalist.
Sectors Other