SciPost logo

NISQ algorithm for the matrix elements of a generic observable

Rebecca Erbanni, Kishor Bharti, Leong-Chuan Kwek, Dario Poletti

SciPost Phys. 15, 180 (2023) · published 30 October 2023


The calculation of off-diagonal matrix elements has various applications in fields such as nuclear physics and quantum chemistry. In this paper, we present a noisy intermediate scale quantum algorithm for estimating the diagonal and off-diagonal matrix elements of a generic observable in the energy eigenbasis of a given Hamiltonian without explicitly preparing its eigenstates. By means of numerical simulations we show that this approach finds many of the matrix elements for the one and two qubits cases. Specifically, while in the first case, one can initialize the ansatz parameters over a broad interval, in the latter the optimization landscape can significantly slow down the speed of convergence and one should therefore be careful to restrict the initialization to a smaller range of parameters.

Ontology / Topics

See full Ontology or Topics database.

Quantum computing

Authors / Affiliations: mappings to Contributors and Organizations

See all Organizations.
Funders for the research work leading to this publication