Accelerated Variational Quantum Eigensolver

Daochen Wang, Oscar Higgott, and Stephen Brierley
Phys. Rev. Lett. 122, 140504 – Published 12 April 2019
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Abstract

The problem of finding the ground state energy of a Hamiltonian using a quantum computer is currently solved using either the quantum phase estimation (QPE) or variational quantum eigensolver (VQE) algorithms. For precision ε, QPE requires O(1) repetitions of circuits with depth O(1/ε), whereas each expectation estimation subroutine within VQE requires O(1/ε2) samples from circuits with depth O(1). We propose a generalized VQE algorithm that interpolates between these two regimes via a free parameter α[0,1], which can exploit quantum coherence over a circuit depth of O(1/εα) to reduce the number of samples to O(1/ε2(1α)). Along the way, we give a new routine for expectation estimation under limited quantum resources that is of independent interest.

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  • Received 18 June 2018
  • Revised 18 December 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.140504

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Daochen Wang*, Oscar Higgott, and Stephen Brierley

  • Riverlane, 3 Charles Babbage Road, Cambridge CB3 0GT, United Kingdom

  • *wdaochen@ gmail.com

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Issue

Vol. 122, Iss. 14 — 12 April 2019

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