Analog gravity in Dirac materials

by Mrs Mireia Tolosa-Siméon (Ruhr-Universität Bochum)

Friday 17 Nov 2023, 15:00 → 16:30 Europe/Berlin

Online seminar on Zoom

https://uni-jena-de.zoom-x.de/j/62202018021?pwd=ekZiSzVnOGtyMGIzZ0lQNk0xc2g1Zz09

Meeting-ID: 622 0201 8021
Kenncode: 869543

Abstract:

Condensed matter systems can be used in various scenarios to emulate and study phenomena from a completely different field of physics, for example, elementary particle physics or gravity. Such analog condensed matter models provide a novel perspective to approach questions that are not directly accessible in the original systems as they can potentially be realized experimentally in a well-controlled setup.

In this project [1], we address the problem of cosmological fermion production in expanding universes using moiré Dirac materials as analog models. Recently, two-dimensional moiré Dirac materials, such as twisted bilayer graphene (TBG), have been established as highly tunable condensed matter platforms allowing us to manipulate electronic band structures and interaction effects in a controlled manner. A remarkable feature of moiré Dirac materials is the presence of fermionic low-energy excitations, described by a quasi-relativistic Dirac equation where the velocity of light is replaced by the Fermi velocity. The Fermi velocity can be tuned dynamically over several orders of magnitude leading to a time-dependent metric for the Dirac fermions. In addition, we consider the presence of time-dependent Dirac masses that may originate from symmetry breaking and lead to a finite band gap in the energy dispersion. These ingredients allow us to construct an analog model for the phenomenon of cosmological fermion production in expanding universes, arising due to a time-dependent metric and conformal symmetry breaking.

[1] M. Tolosa-Simeón, M. M. Scherer and S. Floerchinger, Analog of cosmological particle production in moiré Dirac materials, arxiv:2307.09299 (2023).