Error detection on quantum computers improves accuracy of chemical calculations

TL;DR

This paper demonstrates that quantum error detection, even without full fault tolerance, enhances the accuracy of chemical calculations on current quantum hardware, exemplified by a hydrogen molecule simulation.

Contribution

It provides experimental evidence that quantum error detection improves chemical calculation accuracy on near-term quantum devices without requiring full fault-tolerance.

Findings

Error detection improves molecular energy calculation accuracy

Experiment performed on current quantum hardware

Encoded calculations outperform unencoded ones

Abstract

A major milestone of quantum error correction is to achieve the fault-tolerance threshold beyond which quantum computers can be made arbitrarily accurate. This requires extraordinary resources and engineering efforts. We show that even without achieving full fault tolerance, quantum error detection is already useful on the current generation of quantum hardware. We demonstrate this experimentally by executing an end-to-end chemical calculation for the hydrogen molecule encoded in the [[4, 2, 2]] quantum error-detecting code. The encoded calculation with logical qubits significantly improves the accuracy of the molecular ground-state energy.