Measuring the Capabilities of Quantum Computers

TL;DR

This paper introduces scalable techniques to test and benchmark quantum computers, revealing complex errors that affect their ability to run structured, real-world programs effectively.

Contribution

It presents new methods for efficiently testing quantum computer capabilities and demonstrates their effectiveness on twelve different quantum processors.

Findings

Current hardware exhibits complex, structured errors affecting performance

Standard error metrics do not predict performance on useful programs

The proposed benchmarks are scalable and reliable for real-world applications

Abstract

A quantum computer has now solved a specialized problem believed to be intractable for supercomputers, suggesting that quantum processors may soon outperform supercomputers on scientifically important problems. But flaws in each quantum processor limit its capability by causing errors in quantum programs, and it is currently difficult to predict what programs a particular processor can successfully run. We introduce techniques that can efficiently test the capabilities of any programmable quantum computer, and we apply them to twelve processors. Our experiments show that current hardware suffers complex errors that cause structured programs to fail up to an order of magnitude earlier - as measured by program size - than disordered ones. As a result, standard error metrics inferred from random disordered program behavior do not accurately predict performance of useful programs. Our methods provide efficient, reliable, and scalable benchmarks that can be targeted to predict quantum computer performance on real-world problems.