Topological Entanglement and Clustering of Jain Hierarchy States

TL;DR

This paper investigates the topological and clustering properties of Jain hierarchy states, revealing their structure, entanglement spectrum, and relation to Coulomb ground states, with implications for understanding fractional quantum Hall states.

Contribution

It introduces a squeezing rule for Jain states, analyzes their entanglement spectrum, and demonstrates their universal equivalence to Coulomb ground states at filling 2/5.

Findings

Jain states satisfy a specific clustering and squeezing rule.

The entanglement spectrum of Jain 2/5 states matches Coulomb ground states.

The entanglement gap remains constant in the thermodynamic limit.

Abstract

We obtain the clustering properties and part of the structure of zeroes of the Jain states at filling $\frac{k}{2k+1}$: they are a direct product of a Vandermonde determinant (which has to exist for any fermionic state) and a bosonic polynomial at filling $\frac{k}{k+1}$ which vanishes when $k+1$ particles cluster together. We show that all Jain states satisfy a "squeezing rule" (they are "squeezed polynomials") which severely reduces the dimension of the Hilbert space necessary to generate them. The squeezing rule also proves the clustering conditions that these states satisfy. We compute the topological entanglement spectrum of the Jain $\nu={2/5}$ state and compare it to both the Coulomb ground-state and the non-unitary Gaffnian state. All three states have very similar "low energy" structure. However, the Jain state entanglement "edge" state counting matches both the Coulomb counting as well as two decoupled U(1) free bosons, whereas the Gaffnian edge counting misses some of the "edge" states of the Coulomb spectrum. The spectral decomposition as well as the edge structure is evidence that the Jain state is universally equivalent to the ground state of the Coulomb Hamiltonian at $\nu={2/5}$. The evidence is much stronger than usual overlap studies which cannot meaningfully differentiate between the Jain and Gaffnian states. We compute the entanglement gap and present evidence that it remains constant in the thermodynamic limit. We also analyze the dependence of the entanglement gap and overlap as we drive the composite fermion system through a phase transition.