Exploring fluctuations in Quantum thermal machines

热力学是自然科学的支柱之一：它研究不同温度下物体之间的能量交换方式。这个项目旨在研究当感兴趣的过程涉及像电子、原子或简单分子这样的简单系统时会发生什么。对于这种纳米级的物质构件，必须援引量子力学定律。这些微型热机只有几个原子，有望在从微处理器到化学反应的广泛技术中提供高效的发电、管理热流和回收浪费能源的方法。该项目旨在开发新的数学工具和强大的模拟方法，以了解控制最小可能发动机性能的基本原理。该项目将使用最先进的张量网络方法来模拟与大型电子水库耦合的少量相互作用模式。除了数值方法外，拟议的研究还将包括开放量子系统理论、量子信息理论和统计学的分析技术的混合。然后，该项目将揭示量子相干、耗散和多体关联如何影响系统运行期间流经系统的热和电荷电流的波动以及熵产生。利用热力学不确定关系，这些量将与纳米级自主热机在有限功率输出下的效率有关，这是其功能的关键指标。该项目还将探索与热浴耦合的多体系统中的周期性驱动器件和Floquet加热。其目标是：1.开发一个热力学上一致的多体框架来描述与多个储罐耦合的复杂量子系统的NESS。为了确定复杂量子系统的相互作用、耗散和周期驱动如何影响其作为热机的功能，并提出实验试验台来验证这些影响。通过实现其目标，该项目将对我们对量子区域中非平衡稳态的理解产生实质性影响，并立即为最广泛的量子社区带来好处。特别是，这些发现将与纳米技术、化学、生物学以及潜在的磁性材料和存储设备的工业应用相关。与此同时，该项目将有助于确定量子器件设计中的进一步挑战，并将为新的热力学启发方法奠定基础。该项目属于EPSRC的研究领域：“量子器件、部件和系统”和“量子流体和固体”。它是对EPSRC由斯蒂芬·克拉克博士领导的活跃的QuamNESS(https://gow.epsrc.ukri.org/NGBOViewGrant.aspx?GrantRef=EP/T028424/1)研究项目的补充，合作伙伴包括约翰·古尔德博士(都柏林三一学院)和毛罗·帕特诺斯特罗教授(贝尔法斯特女王学院)。

Thermodynamics is one of the pillars of natural sciences: it studies the way energy is exchanged between bodies at different temperature. This project aims to look at what happens when the processes of interest involve systems as simple as electrons, atoms or simple molecules. For such nanoscale building blocks of matter, the laws of quantum mechanics have to be invoked. Miniaturised to only handfuls of atoms, these thermal machines hold the promise of offering highly efficient ways of generating power, managing heat flows and recovering wasted energy in wide-ranging technologies, from microprocessors to chemical reactions. This project aims to develop novel mathematical tools and powerful simulation methods to understand the fundamental principles governing the performance of the smallest possible engines. The project will use state-of-the-art tensor network methods to simulate a small number of interacting modes coupled to large electronic reservoirs. In addition to numerical methods the proposed research will include a mix of analytical techniques from open quantum systems theory, quantum information theory and statistical. The project will then unravel how quantum coherence, dissipation and many-body correlations influence the fluctuations in heat and charge current flowing across the system as well as entropy production during its operation. Using thermodynamic uncertainty relations these quantities will be related to the efficiency of nanoscale autonomous thermal machine at finite power output, a key metric in its functionality. The project will also explore periodically driven devices and Floquet heating in many-body system coupled to a thermal bath.Its objectives are:1. To develop a thermodynamically consistent many-body framework for describing NESS of complex quantum systems coupled to multiple reservoirs.2. To identify how interactions, dissipation, and periodic driving of complex quantum systems influence their functionality as thermal machines and propose experimental testbeds to verify such effects.By realizing its objectives this project will make a substantive impact in our understanding of non-equilibrium steady states in the quantum regime, with immediate benefits for the broadest quantum community. In particular, the findings will be of relevance for nanotechnology, chemistry, biology and, potentially, industrial applications in magnetic materials and memory devices. At the same time the project will help identify further challenges in the design of quantum devices and will lay the foundations of new thermodynamically inspired approaches.This project falls within the EPSRC research areas: "Quantum devices, components and systems" and "Quantum fluids and solids". It complements an active EPSRC research project QuamNESS (https://gow.epsrc.ukri.org/NGBOViewGrant.aspx?GrantRef=EP/T028424/1) led by Dr Stephen Clark and involves collaborators Dr John Goold (Trinity College, Dublin) and Prof Mauro Paternostro (Queen's Belfast).