Holographic quantum fluids

量子流体是一种非常规类型的流体（气体或液体），具有奇异的性质，只能用量子力学来解释。例如，量子流体具有一种称为超流体成分的非粘性成分，在非常小的温度极限（在绝对零度附近），其百分比趋于100%；这种性质使得非常冷的量子流体几乎永远以粘度的形式运动，导致像水或蜂蜜这样的经典流体在时间上变慢，趋于零。超流体组件的另一个显著特性是能够容纳只有离散循环值的漩涡（流体旋转的区域），换句话说，它们的强度是量化的。尽管大约100年前在低温下冷却液氦时发现了量子流体，但今天已知的大多数量子流体是在过去20年里才通过实验实现的。它们的技术用途仍然非常有限，但很有希望，因为人们相信，在未来几十年里，它们可以越来越多地用于制造令人难以置信的精确传感器，用于量子计算，以及作为非常有效的传热介质。然而，为了实现这些目标，更好地了解它们的特性是至关重要的。这一提议旨在更好地理解量子流体，其特征是强相互作用，例如冷液氦。由于它们之间的强相互作用，标准的理论方法如微扰方法无法为这类系统提供模型。我们建议使用过去二十年来在高能粒子物理和弦理论领域发展起来的一个理论框架来解决建模问题，这个理论框架被称为全息二象性/全息理论。简而言之，全息术允许通过将强相互作用系统映射到弯曲时空中更高维度的弱相互作用系统来找到强相互作用系统的模型描述。这种方法无疑增加了问题的复杂性，但允许在弱相互作用的对应物中应用标准微扰方法。更准确地说，可以尝试理论和数值方法，从而允许有效地模拟强相互作用的系统。全息二象性已被应用于凝聚态和粒子物理中的各种物理系统，包括量子流体。然而，直到最近几年，由于新的数值方法的发展和计算能力的提高，量子流体的动力学建模才成为可能。提出的研究将极大地扩展这些工作，并允许模型系统更相关的实验设置和发现，希望，新的物理！

A quantum fluid is an unconventional type of fluid (gas or liquid) with exotic properties that can only be explained invoking quantum mechanics. For example, a quantum fluid possesses an inviscid component called superfluid component, whose percentage tends to 100% in the limit of very small temperatures (around the absolute zero); such property makes a very cold quantum fluid moving almost forever as viscosity, causing a classical fluid like water or honey to slow down in time, tends to zero. Another striking property of the superfluid component is the ability to host vortices (regions where the fluid rotates) that have only discrete values of circulation, in other words meaning that their strength is quantised.Despite being discovered about a hundred years ago when cooling down liquid helium at very low temperatures, most of the quantum fluids known today have only been experimentally realised in the last two decades. Their technological uses are still very limited but promising, as it is believed that in the next decades they could be used more and more to make incredibly precise sensors, in quantum computing, and as very efficient media to transport heat. However, in order to achieve these goals, a better understanding of their properties is of paramount importance.This proposal aims at better understanding quantum fluids characterised by strong interactions like for example, cold liquid helium. Due to their strong interactions, standard theoretical methods like perturbative methods fail to provide models for such systems. We propose to tackle the modelling by using a theoretical framework developed in the past two decades in the field of high energy particle physics and string theory called holographic duality / holography theory. In a nutshell, holography allows to find a model description of strong interacting systems by mapping them into weakly interacting systems at higher dimensions in curved space-time. This method certainly increases the complexity of the problem but allows to apply standard perturbative methods within the weakly interacting counterparts. More precisely, theoretical and numerical approaches can be attempted, therefore allowing to effectively model strongly interacting systems.The holographic duality has been applied to a great variety of physical systems in condensed matter and particle physics, including quantum fluids before. However, only in the last couple of years, dynamical modelling of quantum fluids have been feasible thanks to the development of novel numerical methods and the improvement of computational power. The proposed research will greatly extend these works and allow to model systems which are more relevant to experimental setups and discover, hopefully, new physics!