Benchmarking Noisy Intermediate Scale Quantum Error Mitigation
  Strategies for Ground State Preparation of the HCl Molecule
Due to numerous limitations including restrictive qubit topologies, short
coherence times and prohibitively high noise floors, few quantum chemistry
experiments performed on existing noisy intermediate-scale quantum hardware
have achieved the high bar of chemical precision, namely energy errors to
within 1.6 mHa of full configuration interaction. To have any hope of doing so,
we must layer contemporary resource reduction techniques with best-in-class
error mitigation methods; in particular, we combine the techniques of qubit
tapering and the contextual subspace variational quantum eigensolver with
several error mitigation strategies comprised of measurement-error mitigation,
symmetry verification, zero-noise extrapolation and dual-state purification. We
benchmark these strategies across a suite of eight 27-qubit IBM Falcon series
quantum processors, taking preparation of the HCl molecule's ground state as
our testbed.
Tim Weaving Alexis Ralli William M. Kirby Peter J. Love Sauro Succi Peter V. Coveney