The Road to Useful Quantum Computers

TL;DR

This paper reviews the progress, challenges, and future prospects of developing practical, useful quantum computers capable of solving important scientific and real-world problems, emphasizing key scientific and engineering hurdles.

Contribution

It provides a comprehensive overview of current quantum computing capabilities, compares them to utility requirements, and discusses strategies to achieve practical quantum advantage.

Findings

Quantum computers have advanced from small experiments to prototypes.

Current quantum systems are far from achieving quantum utility.

Identifies key scientific and engineering challenges on the path to useful quantum computing.

Abstract

Building a useful quantum computer is a grand science and engineering challenge, currently pursued intensely by teams around the world. In the 1980s, Richard Feynman and Yuri Manin observed independently that computers based on quantum mechanics might enable better simulations of quantum phenomena. Their vision remained an intellectual curiosity until Peter Shor published his famous quantum algorithm for integer factoring, and shortly thereafter a proof that errors in quantum computations can be corrected. Since then, quantum computing R&D has progressed rapidly, from small-scale experiments in university physics laboratories to well-funded industrial efforts and prototypes. Hype notwithstanding, quantum computers have yet to solve scientifically or practically important problems -- a target often called quantum utility. In this article, we describe the capabilities of contemporary quantum computers, compare them to the requirements of quantum utility, and illustrate how to track progress from today to utility. We highlight key science and engineering challenges on the road to quantum utility, touching on relevant aspects of our own research.