Dynamical Electromagnetism in Holography

Understanding the anomalous transport properties of strange metals—such as those found in high-temperature superconductors—remains one of the central open problems in condensed matter physics. Holographic duality, originally developed in high-energy physics, can offer insights into these systems. Most of the holographic models have only considered systems subject to an external gauge (electric) field, as is suitable for determinining e.g., the electrical conductivity. However, the density-density correlation function - which governs the plasmon response of the system - requires electromagnetism to be treated dynamically. Recent experiments on the plasmon response in strange metals has shown that is its strongly damped: indeed, in holographic models that properly treats dynamical electromagnetism, a fininte damping even at zero momentum is a robust feature.

I have worked on properly formulating the entire dynamical E&M framework within holography; how to obtain full dielectric function (and the permittivity), which gives access to the D- and H-fields within the materials, and how to consider general geometric setups (e.g., a slab geometry). In particular, we have stuided the surface plasmon polariton response. The paper is in progress, but preliminary results can be found in my PhD thesis (Nilsson, 2026).

We have also implemented dynamical electromagnetism into models of strongly correlated Ersatz Fermi liquids, which results in a plasmon mode whose plasma frequency is related to the charge density contained in an explicit Fermi surface, rather than to the charge density of a charged black hole (missing reference)

References

Ph.D. thesis
Transport and Collective Dynamics in Fermi and Non-Fermi Liquids

Eric Nilsson

Chalmers University of Technology, Jun 2026

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Modern quantum materials host a wide range of electronic phases in which transport properties are governed by strong interactions and collective effects. This thesis investigates charge, heat, and momentum transport in interacting electronic systems across different theoretical frameworks, ranging from Fermi liquid theory to strongly coupled strange metals. The first part of the thesis focuses on two-dimensional Fermi liquids at finite temperature, where rapid electron-electron scattering can give rise to hydrodynamic behavior. A kinetic-theory framework allowing an exact treatment of quasiparticle distribution functions beyond the asymptotic low-temperature regime is used to compute the full spectrum of collective modes, providing a detailed characterization of long-lived odd-parity excitations and the intermediate transport regime between ballistic and hydrodynamic flow. The same framework is employed to determine the shear viscosity of interacting electron liquids beyond conventional perturbative limits. The second part of the thesis concerns strongly interacting quantum systems where the quasiparticle picture breaks down. Holographic duality is used to study transport and thermoelectric response in quantum critical systems subject to periodic potentials, providing a controlled framework for momentum relaxation and magnetotransport in non-Fermi liquids. The thesis further develops holographic models of collective charge dynamics in systems with dynamical electromagnetism, including bulk plasmons and surface plasmon polaritons, and explores connections between Fermi surface physics and holographic gauge-field dynamics.
@phdthesis{nilsson_transport_2026, title = {Transport and {{Collective Dynamics}} in {{Fermi}} and {{Non-Fermi Liquids}}}, author = {Nilsson, Eric}, year = {2026}, month = jun, doi = {10.63959/chalmers.dt/5874}, urldate = {2026-05-29}, isbn = {978-91-8103-417-2}, langid = {english}, school = {Chalmers University of Technology}, ulr = {https://research.chalmers.se/publication/552070}, }