Few-qubit quantum-classical simulation of strongly correlated lattice fermions

TL;DR

This paper demonstrates a minimal quantum-classical hybrid simulation approach for strongly correlated fermion models using only four qubits, paving the way for near-term quantum simulations of complex materials.

Contribution

It introduces a two-site DMFT method implemented with a four-qubit quantum circuit, simplifying the simulation of strongly correlated systems.

Findings

Feasible implementation with superconducting circuits

Reduction of the impurity problem to four qubits

Potential for near-term quantum simulations

Abstract

We study a proof-of-principle example of the recently proposed hybrid quantum-classical simulation of strongly correlated fermion models in the thermodynamic limit. In a "two-site" dynamical mean-field theory (DMFT) approach we reduce the Hubbard model to an effective impurity model subject to self-consistency conditions. The resulting minimal two-site representation of the non-linear hybrid setup involves four qubits implementing the impurity problem, plus an ancilla qubit on which all measurements are performed. We outline a possible implementation with superconducting circuits feasible with near-future technology.