Emergent polaronic correlations in doped spin liquids

TL;DR

This paper introduces a variational wavefunction approach to study doped quantum spin liquids, revealing emergent polaronic correlations and achieving quantitative agreement with cold-atom experiments on the Hubbard model.

Contribution

It develops a new variational method that fully incorporates gauge fluctuations, providing a more accurate description of doped spin liquids than previous mean-field approaches.

Findings

Demonstrates emergence of magnetic polaron correlations in doped spin liquids.

Achieves quantitative agreement with cold-atom measurements of the Hubbard model.

Provides a new variational framework for studying fractionalized metallic states.

Abstract

The interplay between spin and charge degrees of freedom arising from doping a Mott insulating quantum spin liquid (QSL) has been a topic of research for several decades. Calculating properties of these fractionalized metallic states in single-band models are generally restricted to mean-field patron descriptions and small fluctuations around these states, which are insufficient for quantitative comparison of observables to measurements performed in strongly-correlated systems. In this work, we numerically study a class of correlated electronic wavefunctions which support fractionalized spin and charge excitations and which fully take into account gauge fluctuations through the enforcement of local Hilbert space constraints. By optimizing the energy of these wavefunctions against the hole-doped Fermi Hubbard Hamiltonian, we obtain a variational ansatz for describing the low-energy physics of this model. We compare measurements of hole-induced spin-spin correlation functions to measurements taken in low temperature cold-atom simulations of the Hubbard model and find quantitative agreement between the two. In particular, we demonstrate the emergence of magnetic polaron correlations in these metallic states.