Lazy Quantum Walks with Native Multiqubit Gates

TL;DR

This paper explores implementing lazy quantum walks using native multiqubit gates on neutral atom platforms, demonstrating advantages over decomposed gates through detailed error modeling and simulations.

Contribution

It introduces a quantum half-adder gate method for quantum walks and analyzes the benefits of native multiqubit gates in neutral atom systems.

Findings

Native multiqubit gates can outperform decomposed gates in fidelity.

Simulations identify optimal conditions for multiqubit gate advantages.

Lazy quantum walks are feasible with realistic error models.

Abstract

Quantum walks, the quantum analogue of the classical random walk, have been shown to underpin quantum algorithms for fluid dynamics. We propose the quantum half-adder gate method for quantum walks as a good benchmark algorithm, specifically to compare native two-qubit gate and native multiqubit gate implementations. Neutral atom hardware is a promising choice of platform for implementing quantum walks due to its ability to implement native multiqubit (>2-qubit) gates and to dynamically re-arrange qubits. Using detailed realistic error modelling for multiqubit Rydberg gates via two-photon adiabatic rapid passage, we present the gate sequences and predicted final state fidelities for some small one dimensional quantum walks, including lazy quantum walks; lazy quantum walks include a rest state, which is needed for quantum walks for fluid simulation. Our simulations pinpoint the sweet spot where native multiqubit gates provide an advantage compared with decomposing the gate into multiple smaller higher fidelity gates.