Gapless layered three-dimensional fractional quantum Hall states

TL;DR

This paper constructs a novel 3D multilayer fractional quantum Hall state with unique quasiparticle and collective mode properties, distinct from stacked Laughlin states, potentially realizable in multilayer systems with intermediate tunneling.

Contribution

It introduces a gapless, layered 3D fractional quantum Hall state using the parton approach, featuring propagating quasiparticles and emergent photons, different from prior stacked Laughlin states.

Findings

Supports gapped charge e/3 quasiparticles propagating between layers

Contains gapless neutral collective modes resembling an emergent photon

Proposes realization in multilayer systems with intermediate tunneling

Abstract

Using the parton construction, we build a three-dimensional (3D) multilayer fractional quantum Hall state with average filling \nu = 1/3 per layer that is qualitatively distinct from a stacking of weakly coupled Laughlin states. The state supports gapped charge e/3 fermionic quasiparticles that can propagate both within and between the layers, in contrast to the quasiparticles in a multilayer Laughlin state which are confined within each layer. Moreover, the state has gapless neutral collective modes, a manifestation of an emergent "photon", which is minimally coupled to the fermionic quasiparticles. The surface sheath of the multilayer state resembles a chiral analog of the Halperin-Lee-Read state, which is protected against gap forming instabilities by the topological character of the bulk 3D phase. We propose that this state might be present in multilayer systems in the "intermediate tunneling regime", where the interlayer tunneling strength is on the same order as the Coulomb energy scale. We also find that the parton construction leads to a candidate state for a bilayer \nu = 1/3 system in the intermediate tunneling regime. The candidate state is distinct from both a bilayer of \nu=1/3 Laughlin states and the single layer \nu = 2/3 state, but is nonetheless a fully gapped fractional quantum Hall state with charge e/3 anyonic quasiparticles.