Polaritonic excited state properties on superconducting processors

In polaritonic chemistry, strong light-matter interactions between molecular matter and cavity photons can alter chemical reactions. The recent advent of quantum algorithms for noisy quantum devices offers a new route toward simulating complex polaritonic systems. Building on previous work that uses the variational quantum eigensolver (VQE) to calculate polaritonic ground state energies [1,2], we extend these methods to compute the excited-state properties of polaritonic systems. Using the polaritonic unitary coupled cluster (PUCC) ansatz with the VQE to obtain the ground state, we use the quantum equation of motion (qEOM) [3] method to calculate excitation energies, transition dipole moments, and Rabi splittings. We explore the robustness of this approach across a diverse set of regimes for the bond length, cavity frequency, and coupling strength of the H₂ molecule in an optical cavity.

[1] F. Pavošević and J. Flick, J. Phys. Chem. Lett., 12, 37, 9100–9107 (2021).

[2] M. Hassan, F. Pavošević, D.S. Wang, and J. Flick, J. Phys. Chem. Lett., 15 (5), 1373-1381 (2024).

[3] P.J. Ollitrault, A. Kandala, C. Chen, P.Kl. Barkoutsos, A. Mezzacapo, M. Pistoia, S. Sheldon, S. Woerner, J.M. Gambetta, and I. Tavernelli, Phys. Rev. Res., 2, 043140 (2020).