Variational quantum solver employing the PDS energy functional
- URL: http://arxiv.org/abs/2101.08526v7
- Date: Tue, 22 Jun 2021 17:44:55 GMT
- Title: Variational quantum solver employing the PDS energy functional
- Authors: Bo Peng, Karol Kowalski
- Abstract summary: A new class of quantum algorithms that are based on the quantum computation of the connected moment expansion has been reported to find the ground and excited state energies.
Here we find that the Peeters-Devreese-Soldatov (PDS) formulation is found variational and bearing the potential for further combining with the existing variational quantum infrastructure.
In comparison with the usual variational quantum eigensolver (VQE) and the original static PDS approach, this new variational quantum solver offers an effective approach to navigate the dynamics to be free from getting trapped in the local minima.
- Score: 6.822193536884916
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: Recently a new class of quantum algorithms that are based on the quantum
computation of the connected moment expansion has been reported to find the
ground and excited state energies. In particular, the Peeters-Devreese-Soldatov
(PDS) formulation is found variational and bearing the potential for further
combining with the existing variational quantum infrastructure. Here we find
that the PDS formulation can be considered as a new energy functional of which
the PDS energy gradient can be employed in a conventional variational quantum
solver. In comparison with the usual variational quantum eigensolver (VQE) and
the original static PDS approach, this new variational quantum solver offers an
effective approach to navigate the dynamics to be free from getting trapped in
the local minima that refer to different states, and achieve high accuracy at
finding the ground state and its energy through the rotation of the trial wave
function of modest quality, thus improves the accuracy and efficiency of the
quantum simulation. We demonstrate the performance of the proposed variational
quantum solver for toy models, H$_2$ molecule, and strongly correlated planar
H$_4$ system in some challenging situations. In all the case studies, the
proposed variational quantum approach outperforms the usual VQE and static PDS
calculations even at the lowest order. We also discuss the limitations of the
proposed approach and its preliminary execution for model Hamiltonian on the
NISQ device.
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