Bonn 2025 – scientific programme
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QI: Fachverband Quanteninformation
QI 12: Quantum Computing Theory II
QI 12.4: Talk
Tuesday, March 11, 2025, 12:00–12:15, HS IV
Ordering operators for an effective ansatz in VQE calculations — •Sahil Sarbadhikary, Walter Hahn, and Thomas Wellens — Fraunhofer IAF, Freiburg im Breisgau, Germany
The Variational Quantum Eigensolver (VQE) is a promising candidate for a quantum algorithm with near-term applications. It aims to solve a problem central to quantum chemistry: computing the ground state energy of a Hamiltonian describing a molecule. To implement an ansatz for the variational wave function on a quantum computer, the first-order Suzuki-Trotter expansion is usually used, which entails the problem of the non-equivalent order of the operators defining the ansatz. In this talk, we explore the effect of the order of operators in the ansatz on the accuracy of VQE calculations by considering different molecules. We show that the order of operators has an impact on the accuracy of VQE calculations and evaluate possible effective ordering schemes.
Keywords: Variational Quantum Eigensolver; Hamiltonian; ordering; Suzuki-Trotter; quantum chemistry