The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases

Momentum-conserving quasiparticle collisions in two-dimensional Fermi gases give rise to a large family of exceptionally long-lived excitation modes. The lifetimes of these modes exceed by a factor \((T_F/T)^2\gg 1\) the conventional Landau Fermi-liquid lifetimes \(\tau\sim T_F/T^2\). The long-lived...

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Bibliographic Details
Published in:arXiv.org 2019-05
Main Authors: Ledwith, Patrick J, Guo, Haoyu, Levitov, Leonid
Format: Article
Language:English
Subjects:
Excitation
Fermi gases
Fermi surfaces
Time dependence
Online Access:Get full text
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Summary:Momentum-conserving quasiparticle collisions in two-dimensional Fermi gases give rise to a large family of exceptionally long-lived excitation modes. The lifetimes of these modes exceed by a factor \((T_F/T)^2\gg 1\) the conventional Landau Fermi-liquid lifetimes \(\tau\sim T_F/T^2\). The long-lived modes have a distinct angular structure, taking the form of \(\cos m\theta\) and \(\sin m\theta\) with odd \(m\) values for a circular Fermi surface, with relaxation rate dependence on \(m\) of the form \(m^4\log m\), valid at not-too-large \(m\). In contrast, the even-\(m\) harmonics feature conventional lifetimes with a weak \(m\) dependence. The long-time dynamics, governed by the long-lived modes, takes the form of angular (super)diffusion over the Fermi surface. Altogether, this leads to unusual long-time memory effects, defining an intriguing transport regime that lies between the conventional ballistic and hydrodynamic regimes.
ISSN:2331-8422
DOI:10.48550/arxiv.1905.03751