March 18, 2022

Reducing the Cost of Energy Estimation in VQE with RAE

  • Peter Johnson
  • Alex Kunitsa
  • Max Radin
  • Jhonathan Romero Fontalvo

Quantum chemistry and materials is one of the most promising applications of quantum computing. Yet much work is still to be done in matching industry-relevant problems in these areas with quantum algorithms that can solve them.

Most previous efforts have carried out resource estimations for quantum algorithms run on large-scale fault-tolerant architectures, which include the quantum phase estimation algorithm. In contrast, few have assessed the performance of near-term quantum algorithms, which include the variational quantum eigensolver (VQE) algorithm.

Recently, a large-scale benchmark study found evidence that the performance of the variational quantum eigensolver for a set of industry-relevant molecules may be too inefficient to be of practical use. This motivates the need for developing and assessing methods that improve the efficiency of VQE. In this work, we predict the runtime of the energy estimation subroutine of VQE when using robust amplitude estimation (RAE) to estimate Pauli expectation values. Under conservative assumptions, our resource estimation predicts that RAE can reduce the runtime over the standard estimation method in VQE by one to two orders of magnitude. Despite this improvement, we find that the runtimes are still too large to be practical. These findings motivate two complementary efforts towards quantum advantage: 1) the investigation of more efficient near-term methods for ground state energy estimation and 2) the development of problem instances that are of industrial value and classically challenging, but better suited to quantum computation.

External Co-Authors:
  • bp Group Research: Corneliu Buda, Eric J. Doskocil, Clena M. Abuan

  • Jerome Gonthier
Peter Johnson
Zapata Author

Peter Johnson , Ph.D.

Lead Research Scientist & Co-Founder
Alex Kunitsa
Zapata Author

Alex Kunitsa , Ph.D.

Quantum Application Scientist, Professional Services
Max Radin
Zapata Author

Max Radin , Ph.D.

Lead Quantum Software Engineer
Jhonathan Romero Fontalvo
Zapata Author

Jhonathan Romero Fontalvo , Ph.D.

Director of Professional Services & Co-Founder