H2020Индивидуална стипендия2021–2023

QuasiHydro · Beyond hydrodynamics

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2021-12-01 → 2023-11-30
Финансиране от ЕС: 196 708 €
Участници: 1
Схема: MSCA-IF

Линиите свързват координатора с партньорите.

Накратко на български

Квазихидродинамиката изследва системи, в които енергията и частиците не се запазват стриктно, за разлика от стандартните течности. Математическото описание на тези процеси е недостатъчно развито, затова е важно да се създадат по-точни модели за достигане на равновесие.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Beyond hydrodynamics

For an intuitive model of a fluid one can think of a box filled with many, many randomly moving balls that are constantly colliding with one another. From this perspective it is not hard to see that if one were to reach into the box and flick one of the balls to move it at a higher speed, the perturbed ball will quickly lose its additional speed through collisions with the other balls. However, if we were instead to take all the balls and place them in one corner of the box, because they can only spread out randomly and by colliding with each other, the balls will take time to diffuse into the rest of the box. The end result in both cases will be that the balls are roughly evenly spaced in the box if seen from a distance. The flick is a short-time process, while the diffusion is a slow one. It is these slow processes that are described by hydrodynamics. Key to hydrodynamics are the concepts of equilibrium (when the balls eventually are uniformly spread in the box) and conservation (the number of balls does not change). Consequently, the mathematics of hydrodynamics describes how the density of conserved charges (e.g. the total number of balls) in space evolves in time until the system reaches equilibrium. In particular hydrodynamics is typically formulated as conservation laws of energy, momentum and particle number in a “gradient expansion” which tells us how the densities of these quantities differ from global equilibrium as we move through the system (box). However, it is not always the case that the systems we wish to describe have exactly conserved energy, momentum and charge. We have now entered the regime of “quasihydrodynamics” or “relaxed hydrodynamics”. The mathematical description of relaxed hydrodynamics is far less developed than its hydrodynamic cousin, and yet it is important to describe exotic states of matter (such as strange metals), traffic flows and active matter. The main goal of this project was to develop the quasihydrodynamic formalism taking inspiration from observations in gauge-gravity duality.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

What do black holes and particular exotic materials, where strong correlations preclude any description based on weakly-coupled quasiparticles, have in common? Their low energy dynamics are expected to fall within the regime of effective field theories, such as hydrodynamics, where the dynamics are governed by the flow of conserved densities based on the symmetries of the system. However it is often hard to know what the boundaries of this regime are. This is even more true when a system is “quasi”-hydrodynamic meaning one of the conserved quantities, such as the number of particles, decays due to the presence of a “breaking parameter”.Gauge/gravity dualities are relationships from string theory that connect classical black holes to particular quantum theories that have the unusual property of rapidly becoming (quasi)hydrodynamic when perturbed. I seek to use gauge/gravity dualities to answer the following questions: When is quasihydrodynamics a good description of nature (in particular for large values of the breaking parameter)? For what ranges of parameters is it applicable? The first question can be explored by considering models of interdisciplinary relevance and searching for commonalities through which we can categorise them. To answer the second we can make use of the special properties of gauge/gravity theories - the existence of relationships between distinct models (dualities) to compute new results from old.The Marie Curie fellowship will allow me to strengthen my position as the intermediary between condensed matter and string theory, with this project as the initial bridging point. I will use the fellowship to increase my output in high impact journals (e.g. Physical Review Letters), apply for longer term grants and gain knowledge in a new area of physics (condensed matter) through the guidance and experience of my project supervisor Dr.~Blaise Goutéraux. He is the ideal host for this proposal, having extensive experience in these areas.

Оригинален текст от CORDIS (на английски).

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