Rapid counter-diabatic sweeps in lattice gauge adiabatic quantum computing

TL;DR

This paper introduces a variational counter-diabatic protocol for lattice gauge quantum computing that significantly improves ground state preparation fidelity using local, time-dependent magnetic fields optimized via classical methods.

Contribution

It develops a novel variational counter-diabatic approach with local fields for lattice gauge quantum computing, enhancing fidelity without increasing the energy gap.

Findings

Enhanced ground state fidelity compared to quantum annealing.

Protocol relies on local, time-dependent magnetic fields.

Optimized with a single classical parameter.

Abstract

We present a coherent counter-diabatic quantum protocol to prepare ground states in the lattice gauge mapping of all-to-all Ising models (LHZ) with considerably enhanced final ground state fidelity compared to a quantum annealing protocol. We make use of a variational method to find approximate counter-diabatic Hamiltonians that has recently been introduced by Sels and Polkovnikov [Proc. Natl. Acad. Sci. 114, 3909 (2017)]. The resulting additional terms in our protocol are time-dependent local on-site y-magnetic fields. These additional Hamiltonian terms do not increase the minimal energy gap, but instead rely on coherent phase maximization. A single free parameter is introduced which is optimized via classical updates. The protocol consists only of local and nearest-neighbor terms which makes it attractive for implementations in near term experiments.