Redrawing the boundaries: new approaches to many-body open quantum systems

我提出了一个新的视角和方法来理解量子系统及其周围环境之间的相互作用和相互作用。通过重新划定我们称之为系统的东西和我们称之为环境的东西之间的界限，我将提供一个统一的框架，它将允许在分析比目前可能的更大、更复杂的系统方面取得突破。这将导致在许多设置的基础和应用物理学的重要新见解。由数千个原子组成的纳米级系统的行为由量子物理学主导，这可能导致令人惊讶的强大集体特征。打个比方，考虑一下运动场上一群人的合作行为，他们齐声唱歌，尽管有很多声音，但歌曲还是能被分辨出来。同样，在纳米尺度系统中，量子相关性可以在许多组成原子之间共享，使它们在许多情况下表现为单一实体。在过去的十年里，科学研究中最具活力和最令人兴奋的领域之一就是寻求理解，控制和利用这些相关性用于技术应用。这一领域的进一步发展--这可能导致下一次技术革命--需要对物质复杂的量子性质有前所未有的理解。这是一个巨大的挑战，但也是从事这一迷人研究领域的核心原因。利用纳米尺度系统的量子特性的主要障碍是由于没有任何物理系统可以完全与其周围环境的影响隔离。这种巨大、波动且不受控制的环境施加的力会导致系统属性出现不必要的随机变化，即噪音。回到我们的类比，这类似于每个人群成员随机唱一首歌，而不考虑其他人的歌曲，结果（这实际上是噪音！）在量子领域，噪声过程尤其有害。除了模糊我们在探测系统时学到的信息外，与环境的相互作用还可能破坏量子态本身的本质。从量子技术的角度来看，噪音似乎使我们的系统完全无用，至少这是传统的观点。然而，我的研究计划的一个令人兴奋的目标是提供一个可行的替代观点在量子过程中的噪声的作用。想象一群人在唱不同的歌。根据这些群体如何形成、竞争和进化，我们仍然可以在喧嚣之下感知到一些结构。事实上，通过对量子系统与其环境之间的相互作用形成新的统一认识，我将证明，噪声过程实际上可以被利用来驱动系统进入奇异的、健壮的和有用的量子状态。事实上，一系列开创性的实验表明，量子效应和噪声之间的相互作用可能出乎意料地存在于细菌、藻类和植物的自然光捕获网络中。因此，这些系统目前是激烈探索和辩论的主题，其动机是量子物理学可能在生命的基本过程中发挥重要作用的非凡可能性。此外，通过了解这是否有助于自然系统实现强大而有效的太阳能转换，我的目标是开发量子技术的新设计原则，将太阳光作为一种清洁，可持续和高效的能源。通过解决量子物理学的核心问题和在实验室中利用量子过程的主要障碍，我的研究将影响广泛的领域和技术，为未来具有深远社会和经济意义的应用铺平了道路。

I propose a new perspective and approach to understanding the interactions and interplay between quantum systems and their surrounding environments. By redrawing the boundary between what we term the system and what we term the environment, I shall provide a unified framework that will permit a breakthrough in the analysis of larger and more complex systems than presently possible. This will result in important new insights into both fundamental and applied physics across numerous settings. The behaviour of nanoscale systems comprising up to several thousand atoms is dominated by quantum physics, which can lead to surprisingly strong collective features. As an analogy, consider the cooperative behaviour of a crowd at a sports ground who sing in unison, allowing songs to be discerned despite the many voices. Likewise, in nanoscale systems quantum correlations can be shared across numerous constituent atoms, enabling them to behave as single entities in many situations. One of the most dynamic and exciting areas of scientific research over the past decade has been the quest to understand, control, and exploit these correlations for technological applications. Further progress in the field - which could lead to the next technological revolution - requires the development of an unprecedented level of understanding of the intricate quantum nature of matter. This is a formidable challenge, but also a central reason to engage in this fascinating area of research.A primary obstacle to exploiting quantum features of nanoscale systems arises due to the fact that no physical system can ever be completely isolated from the influence of its surroundings. The forces exerted by this large, fluctuating, and uncontrolled environment give rise to unwanted random variations in the system's properties, known as noise. Returning to our analogy, this is akin to each crowd member randomly singing a song with no regard to the songs of others, with the result (which would literally be noise!) that a listener would perceive no underlying structure.In the quantum realm noisy processes are particularly harmful. As well as obscuring the information we learn as we probe a system, interactions with the environment can destroy the very nature of the quantum state itself. From a quantum technology point of view, noise thus seems to render our system to be completely useless.This is the conventional view, at least. However, one of the exciting aims of my research programme is to give a viable alternative perspective on the role of noise in quantum processes. Imagine a crowd in which groups are singing different songs. Depending on how these groups form, compete, and evolve we may still perceive some structure beneath the din. In fact, by developing a new and unified understanding of the interactions between quantum systems and their environments I shall show that noisy processes can actually be harnessed to drive systems into exotic, robust, and useful quantum states.Indeed, a series of groundbreaking experiments have suggested that interplay between quantum effects and noise may unexpectedly exist in the natural light-harvesting networks of bacteria, algae, and plants. These systems are thus currently the subject of intense exploration and debate, motivated by the remarkable possibility that quantum physics may play an important role in the basic processes of life. Moreover, by understanding whether this helps natural systems to achieve robust and efficient solar-energy conversion, I aim to develop new design principles for quantum technologies that draw on solar light as a clean, sustainable, and efficient energy source.By tackling a core issue in quantum physics and a primary obstacle to exploiting quantum processes in the laboratory, my research will impact across a broad range of fields and technologies, paving the way to future applications of far-reaching social and economic importance as well.