How will quantum computers provide an industrially relevant computational advantage in quantum chemistry?

TL;DR

This paper critically reviews the current state of quantum hardware and algorithms in quantum chemistry, analyzing resource requirements and realistic prospects for quantum advantage in industrial chemical applications.

Contribution

It provides a detailed comparison of classical and quantum computational resources for specific molecules and discusses the practical relevance of quantum advantage in industry.

Findings

Quantum resource estimates for molecules like H2 and Cr2.

Quantum advantage may be achievable for certain active spaces.

Practical applications depend on quantum hardware development progress.

Abstract

Numerous reports claim that quantum advantage, which should emerge as a direct consequence of the advent of quantum computers, will herald a new era of chemical research because it will enable scientists to perform the kinds of quantum chemical simulations that have not been possible before. Such simulations on quantum computers, promising a significantly greater accuracy and speed, are projected to exert a great impact on the way we can probe reality, predict the outcomes of chemical experiments, and even drive design of drugs, catalysts, and materials. In this work we review the current status of quantum hardware and algorithm theory and examine whether such popular claims about quantum advantage are really going to be transformative. We go over subtle complications of quantum chemical research that tend to be overlooked in discussions involving quantum computers. We estimate quantum computer resources that will be required for performing calculations on quantum computers with chemical accuracy for several types of molecules. In particular, we directly compare the resources and timings associated with classical and quantum computers for the molecules H$_2$ for increasing basis set sizes, and Cr$_2$ for a variety of complete active spaces (CAS) within the scope of the CASCI and CASSCF methods. The results obtained for the chromium dimer enable us to estimate the size of the active space at which computations of non-dynamic correlation on a quantum computer should take less time than analogous computations on a classical computer. Using this result, we speculate on the types of chemical applications for which the use of quantum computers would be both beneficial and relevant to industrial applications in the short term.