Materials World Network: Investigations of Quantum Fluctuation Relations Using Superconducting Qubits

在过去的二十年里，非平衡功涨落定理的发展为估计分子系统的自由能差提供了新的工具，揭示了微观系统如何与其环境交换能量，并提供了对热力学第二定律本质的更深层次的理解。然而，虽然像Jarzynski等式这样的关系已经在经典极限中得到了实验验证，但它们仍然需要在量子状态中进行测试。在这个项目中进行的实验，由材料研究部的材料世界网络提供奖励，将利用最先进的超导微波谐振器和超导量子比特，对量子制度中的涨落定理进行首次系统研究。该项目还将提供第一个实验来探索工作的量子力学性质，这是最近才在理论上阐明的。此外，通过与坎皮纳斯大学（Campinas，巴西）和圣卡洛斯物理研究所（Sao Carlos Institute of Physics，巴西）的理论家的密切合作，它将为纳米尺度上耗散的本质和开放量子系统的建模提供基本的见解，尤其是在应用于非平衡涨落定理方面，这仍然是一个开放的理论问题。本研究将支持培养一名研究生和一名博士后，研究纳米尺度量子物理的前沿技术，包括超低温超导器件的制造技术和低噪声测量；它将为学生提供量子力学和统计力学的高级理论技术培训，包括开放量子系统的建模和非平衡涨落定理；它将促进国际合作，不仅包括直接的合作研究，还包括研究学生交流和专题研究的发展，以学生为导向的研究教程。在过去的二十年中，我们对微观和纳米尺度系统如何与它们不可避免地嵌入的环境交换能量的理解取得了重要进展。这些进步的前沿是在某些热力学量之间建立了一系列新的精确的数学关系——例如，可以从一个系统中提取的功与同一系统的能量之间的关系。这些发展无论从基础的角度还是从应用的角度来看都是重要的。例如，这些关系改善了我们对热力学第二定律和不可逆性（即时间之箭）的理解；与此同时，它们提供了对最小规模机器效率限制的更深入的了解，随着技术规模的不断缩小，这是一个至关重要的问题。至关重要的是，虽然这些新的关系已经在广泛的经典微纳米系统中得到了测试和利用，但它们在量子系统中的实验验证仍然是一个开放的挑战。在这个国际合作项目中进行的实验将利用最先进的超导电路来进行第一次系统的研究，以应对这一挑战。这项工作的广泛影响是多方面的：该研究将提供对量子系统中工作和能量耗散性质的基本见解，这对于理解新兴的量子和混合量子技术的潜力具有直接重要性，例如量子辅助传感和量子信息；支持培养1名研究生和1名博士后，研究量子纳米物理的前沿技术和课题；它还将促进国际合作，促进研究学生交流和学生在这些先进的当代课题上的通识教育。

Technical AbstractIn 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.Non-Technical AbstractIn 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.