Non-perturbative gadget for topological quantum codes

TL;DR

This paper introduces a non-perturbative method to simulate topologically ordered quantum systems with two-body Hamiltonians, enabling exact solutions and localized excitations for quantum computing.

Contribution

It presents a novel non-perturbative scheme to realize exactly solvable topological codes with localized excitations using only two-body interactions.

Findings

Supports exact ground state degeneracy

Allows localized quasi-particle excitations

Applicable to toric code and quantum double models

Abstract

Many-body entangled systems, in particular topologically ordered spin systems proposed as resources for quantum information processing tasks, often involve highly non-local interaction terms. While one may approximate such systems through two-body interactions perturbatively, these approaches have a number of drawbacks in practice. Here, we propose a scheme to simulate many-body spin Hamiltonians with two-body Hamiltonians non-perturbatively. Unlike previous approaches, our Hamiltonians are not only exactly solvable with exact ground state degeneracy, but also support completely localized quasi-particle excitations, which are ideal for quantum information processing tasks. Our construction is limited to simulating the toric code and quantum double models, but generalizations to other non-local spin Hamiltonians may be possible.