Loop, String, and Hadron Dynamics in SU(2) Hamiltonian Lattice Gauge Theories

TL;DR

This paper introduces a loop-string-hadron (LSH) reformulation of SU(2) lattice gauge theories that simplifies quantum simulation by directly describing gauge-invariant degrees of freedom and is adaptable to other non-Abelian groups.

Contribution

The paper presents a novel LSH formulation for SU(2) gauge theories that improves simulation efficiency and extends to higher dimensions, incorporating quarks and gauge invariants.

Findings

LSH operators are factorized into ladder operators and diagonal matrices.

The Hamiltonian is explicitly expressed up to three spatial dimensions.

The formalism is adaptable to other non-Abelian gauge groups like SU(3).

Abstract

The question of how to efficiently formulate Hamiltonian gauge theories is experiencing renewed interest due to advances in building quantum simulation platforms. We introduce a reformulation of an SU(2) Hamiltonian lattice gauge theory---a loop-string-hadron (LSH) formulation---that describes dynamics directly in terms of its loop, string, and hadron degrees of freedom, while alleviating several disadvantages of quantumly simulating the Kogut-Susskind formulation. This LSH formulation transcends the local loop formulation of $d+1$-dimensional lattice gauge theories by incorporating staggered quarks, furnishing the algebra of gauge-singlet operators, and being used to reconstruct dynamics between states that have Gauss's law built in to them. LSH operators are then factored into products of "normalized" ladder operators and diagonal matrices, priming them for classical or quantum information processing. Self-contained expressions of the Hamiltonian are given up to $d=3$. The LSH formalism makes little use of structures specific to SU(2) and its conceptual clarity makes it an attractive approach to apply to other non-Abelian groups like SU(3).