Geometric quench and nonequilibrium dynamics of fractional quantum Hall states

TL;DR

This paper explores how geometric quenches in fractional quantum Hall states induce coherent many-body dynamics, revealing the excitation of higher-spin collective modes and connecting theoretical models with numerical simulations.

Contribution

It introduces a geometric quench protocol for FQH states, analytically describes graviton dynamics, and demonstrates the excitation of higher-spin modes in a microscopic model.

Findings

Mass anisotropy quench induces harmonic graviton mode oscillations.

Analytical bimetric theory matches numerical short-time dynamics.

Geometric quenches excite higher-spin collective modes.

Abstract

We introduce a quench of the geometry of Landau level orbitals as a probe of nonequilibrium dynamics of fractional quantum Hall (FQH) states. We show that such geometric quenches induce coherent many-body dynamics of neutral degrees of freedom of FQH fluids. The simplest case of mass anisotropy quench can be experimentally implemented as a sudden tilt of the magnetic field, and the resulting dynamics reduces to the harmonic motion of the spin-$2$ "graviton" mode, i.e., the long wavelength limit of the Girvin-MacDonald-Platzman magnetoroton. We derive an analytical description of the graviton dynamics using the bimetric theory of FQH states, and find agreement with exact numerical simulations at short times. We show that certain types of geometric quenches excite higher-spin collective modes, thus establishing their existence in a microscopic model and motivating an extension of geometric theories of FQH states.