Speaker
Description
Calculating excited states in chemistry is crucial to provide insight into molecular behavior beyond the ground state, enabling innovations in spectroscopy, material sciences, and drug design. While several approaches have been developed to compute excited-state properties, finding the best ratio between computational cost and accuracy remains challenging. The advent of quantum computers brings new perspectives, with the development of quantum algorithms that promise an advantage over classical ones. Most of these new algorithms are inspired from previous classical ones, but with different pros and cons. In this work, we focus on the generalization of the variational principle for many-body excited-states that led to the ensemble variational quantum eigensolver (VQE). We compare the performance of two ensemble VQE approaches, the equi-ensemble1 and weighted-ensemble2 one, and conclude that the equi-ensemble is the way to go.
References:
1. E.K.U Gross, L.N. Oliveira and W. Kohn, Phys. Rev. A. 37, 2805 (1988)
2. Nakanishi, Ken M. , Mitarai, Kosuke and Fujii, Keisuke, Phys. Rev. Res. 1, 033062 (2019).
