Quantum simulation of fermionic systems using hybrid digital-analog quantum computing approach

TL;DR

This paper presents a hybrid digital-analog quantum computing method for simulating fermionic systems, leveraging always-on interactions to avoid standard two-qubit gates, and analyzes optimal qubit connectivity topologies.

Contribution

It introduces a digital-analog approach for fermionic simulation that eliminates the need for two-qubit gates and identifies optimal qubit connectivity topologies.

Findings

Optimal connectivity: chain for spinless fermions.

Optimal connectivity: ladder for spin-1/2 particles.

Effective simulation of Fermi-Hubbard model.

Abstract

We consider a hybrid digital-analog quantum computing approach, which allows implementing any quantum algorithm without standard two-qubit gates. This approach is based on the always-on interaction between qubits, which can provide an alternative to such gates. We show how digital-analog approach can be applied to simulate the dynamics of fermionic systems, in particular the Fermi-Hubbard model, using fermionic SWAP network and refocusing technique. We concentrate on the effects of connectivity topology, spread of interaction constants as well as on errors of entangling operations. We find that an optimal connectivity topology of qubits for the digital-analog simulation of fermionic systems of arbitrary dimensionality is a chain for spinless fermions and a ladder for spin-1/2 particles. Such a simple connectivity topology makes digital-analog approach attracting for the fermionic quantum simulation.