Holographic quantum fluids

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!