In the last two decades, the development of nonequilibrium work fluctuation theorems has yielded new tools for the estimation of free energy differences in molecular systems, shed light on how microscopic systems exchange energy with their environment, and provided a deeper understanding of the nature of the second law of thermodynamics. However, while relations like the Jarzynski equality have been verified experimentally in the classical limit, they remain to be tested in the quantum regime. The experiments conducted in this project, which is supported by an award from the Division of Materials Research's Materials World Network, will utilize state-of-the-art superconducting microwave resonators and superconducting qubits to perform the first systematic investigations of fluctuation theorems in the quantum regime. The project will also provide the first experiments to probe the quantum mechanical nature of work, which has only recently been elucidated theoretically. Moreover, through close collaboration with theorists from the University of Campinas (Campinas, Brazil) and The Sao Carlos Institute of Physics (Sao Carlos, Brazil), it will provide fundamental insight into the nature of dissipation at the nanoscale and the modeling of open quantum systems, most notably in application to nonequilibrium fluctuation theorems, which remains an open theoretical question. This research will support the training of one graduate student and one postdoc in cutting-edge technologies for exploring quantum physics at the nanoscale, including fabrication techniques and low-noise measurement of superconducting devices at ultra-low temperatures; it will provide training to students in advanced theoretical techniques in quantum mechanics and statistical mechanics, including the modeling of open quantum systems and nonequilibrium fluctuation theorems; and it will foster an international collaboration, consisting not only of direct collaborative research but also research student exchange and development of topical, student-oriented research tutorials.
In the last two decades, important advances have been made in our understanding of how systems at the micro and nanoscale exchange energy with the environment in which they are inevitably embedded. At the forefront of these advances has been the development of a new series of precise mathematical relationships between certain thermodynamic quantities - e.g. between the work that can be extracted from a system and the energy of the same system. These developments are important both from a fundamental perspective and an applied one. For example, these relations have refined our understanding of the second law of thermodynamics and irreversibility (i.e. the arrow of time); at the same time, they have provided greater insight into the limitations placed on the efficiency of machines at the smallest scale, a question of paramount importance as technology continues to be scaled down in size. Crucially, while these new relationships have been tested and utilized in a wide range of classical micro and nanoscale systems, their experimental verification in quantum systems remains an open challenge. The experiments conducted in this international collaborative project will utilize state-of-the-art superconducting circuitry to perform the first systematic investigations to meet this challenge. The broader impacts of this work are multifold: the research will provide fundamental insight into the nature of work and energy dissipation in quantum systems, which is of direct importance for understanding the potential of burgeoning quantum and hybrid-quantum technologies - such as quantum-assisted sensing and quantum information; it will support the training and education of one graduate student and one postdoc in cutting-edge techniques and topics in quantum nanoscale physics; and it will foster an international collaboration that promotes research student exchange and the general education of students in these advanced, contemporary topics.
