Hybrid quantum-classical approach to correlated materials

TL;DR

This paper proposes a hybrid quantum-classical method that leverages small quantum computers within classical algorithms to efficiently study complex correlated materials, promising significant advancements in quantum material research.

Contribution

It introduces a novel hybrid approach combining quantum and classical computations to address complex correlated materials more efficiently than classical methods alone.

Findings

Quantum computers solve small impurity problems more accurately.

Hybrid approach enables larger, more precise simulations.

Potential to resolve open questions in quantum materials.

Abstract

Recent improvements in control of quantum systems make it seem feasible to finally build a quantum computer within a decade. While it has been shown that such a quantum computer can in principle solve certain small electronic structure problems and idealized model Hamiltonians, the highly relevant problem of directly solving a complex correlated material appears to require a prohibitive amount of resources. Here, we show that by using a hybrid quantum-classical algorithm that incorporates the power of a small quantum computer into a framework of classical embedding algorithms, the electronic structure of complex correlated materials can be efficiently tackled using a quantum computer. In our approach, the quantum computer solves a small effective quantum impurity problem that is self-consistently determined via a feedback loop between the quantum and classical computation. Use of a quantum computer enables much larger and more accurate simulations than with any known classical algorithm, and will allow many open questions in quantum materials to be resolved once a small quantum computer with around one hundred logical qubits becomes available.