Plasma Oscillations in Holographic Quantum Matter
Doktorsavhandling, 2021

In this thesis we explore strongly correlated matter in the framework of holographic duality. Specifically, we examine the quasinormal modes of such systems, and we extend the current framework to efficiently and naturally cover plasmons and other collective modes that may be found within strongly correlated matter.

The interest in strongly correlated matter is motivated by the presence of a “strange metal” phase both in high temperature superconductors and in near charge neutral graphene, both being materials of immense scientific interest. The strange metal phase is a phase characterized by the absence of quasi-particles. This implies that conventional methods, such as perturbation theory in quantum field theory and Monte Carlo methods fall short of being able to describe the dynamics. Perhaps surprisingly, string theory provides a novel method, capable of precisely describing such systems - the holographic duality.

With the holographic duality, strongly coupled matter is mapped onto a weakly coupled gravity theory in one additional dimension, allowing for a conventional treatment of the dual system.

In this thesis, we extend the existing framework to also describe polarizing media. This is explicitly done in the form of new boundary conditions on the holographic dual, which deviate from previous holographic studies, and we contrast the quasinormal modes previously studied with the emergent collective modes we find for some studied models. We find new results, as well as confirm the predictions of less general models in their respective regions of validity and pave the way for more complex future models.


quasinormal modes

gauge/gravity duality


strong coupling


strongly correlated media

PJ-salen, Fysikgården 2
Opponent: Koenraad Schalm, Universiteit Leiden, The Netherlands


Marcus Tornsö

Subatomär, högenergi- och plasmafysik DP

Quantum matter bears immense potential for a new generation of technology. In the movie industry, explaining a device with the word quantum is basically a get out of jail free card for the device to do whatever the writers want. Whereas this is not quite the case with actual quantum matter, it does hold many very unintuitive and thought impossible qualities of ordinary matter. And in the case of the most extreme quantum matter, of which this thesis appertains to, many apsects still lack a coherent theoretical description. In particular, graphene (Nobel prize 2010) and high temperature superconductors (Nobel prize 1987) are materials that have a phase that is so "quantum'' it is aptly named the "strange metal'' phase. 

A good candidate for a theoretical framework for these materials comes from string theory in the shape of holography. This allows one to circumvent solving a very hard problem, by instead solving an easier problem with an additional spatial dimension.

This thesis contributes to the larger picture of understanding these materials of the future, specifically by studying the theoretical electromagnetic response of such matter in a dynamical way, in various physically interesting settings. One particular direct application of this specialization is plasmonics, i.e. utilizing how the electrons can propagate information, a field of physics where graphene is already a material of particular interest.



Annan fysik

Den kondenserade materiens fysik


Grundläggande vetenskaper



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4992



PJ-salen, Fysikgården 2


Opponent: Koenraad Schalm, Universiteit Leiden, The Netherlands

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