Edge state inner products and real-space entanglement spectrum of trial quantum Hall states

TL;DR

This paper establishes a universal bulk/edge correspondence for fractional quantum Hall trial states, linking edge state inner products to bulk conformal field theory correlators and analyzing the entanglement spectrum using boundary CFT techniques.

Contribution

It provides a general framework for computing edge state inner products and entanglement spectra of FQHE trial wavefunctions using boundary conformal field theory, demonstrating their universality and local structure.

Findings

Inner products of edge states equal bulk CFT correlators in the thermodynamic limit.

Entanglement Hamiltonian is shown to be local along the bipartition cut.

Universal behavior of entanglement spectrum derived from boundary CFT analysis.

Abstract

We consider the trial wavefunctions for the Fractional Quantum Hall Effect (FQHE) that are given by conformal blocks, and construct their associated edge excited states in full generality. The inner products between these edge states are computed in the thermodynamic limit, assuming generalized screening (i.e. short-range correlations only) inside the quantum Hall droplet, and using the language of boundary conformal field theory (boundary CFT). These inner products take universal values in this limit: they are equal to the corresponding inner products in the bulk 2d chiral CFT which underlies the trial wavefunction. This is a bulk/edge correspondence; it shows the equality between equal-time correlators along the edge and the correlators of the bulk CFT up to a Wick rotation. This approach is then used to analyze the entanglement spectrum (ES) of the ground state obtained with a bipartition A\cupB in real-space. Starting from our universal result for inner products in the thermodynamic limit, we tackle corrections to scaling using standard field-theoretic and renormalization group arguments. We prove that generalized screening implies that the entanglement Hamiltonian H_E = - log {\rho}_A is isospectral to an operator that is local along the cut between A and B. We also show that a similar analysis can be carried out for particle partition. We discuss the close analogy between the formalism of trial wavefunctions given by conformal blocks and Tensor Product States, for which results analogous to ours have appeared recently. Finally, the edge theory and entanglement spectrum of px + ipy paired superfluids are treated in a similar fashion in the appendix.