ExcitationSolve - A fast gradient-free optimizer for excitations in fixed and adaptive VQEs

Abstract

In recent years, the variational quantum eigensolver (VQE)[1] has carried the hope of the quantum computing community for achieving quantum utility. It aims to find the ground state and corresponding energy of a molecular hamiltonian by classically optimizing the parameters $\theta_j$ of a variational quantum circuit. In order to guarantee the conservation of qunatities such as particle number or spin, physically inspired ansätze such as the UCCSD ansatz are most promising. ExcitationSolve provides a quantum-aware optimizer for such physically inspired ansätze, making best use of prior knowlege about the operators used in the ansatz.