Tackling Electronic Correlations

Massimo Mella, Gabriele Morosi

In Nanostructures

Markus Wallerberger, Hiroshi Shinaoka, Hirone Ishida +6 more

In my talk, I argue that in order to solve the problem of electronic correlation in solids, we need to understand and leverage its structure. To that end, I expose the idea of "latent space" and aim to show its connection to the ancient greek theory of Forms, to techniques already used in physics and chemistry, and to modern machine-learning. Finally, I show how the separation and coupling of length and time scales prevalent in physics can be understood as such latent spaces. This will give rise to quantics tensor trains (QTTs), a powerful and promisting tool for tackling the problem of many correlated electrons.

Xinan Xu, Chee Wei Wong

M. Michael Denner, Alexander Miessen, Haoran Yan +4 more

Interactions between electrons and phonons play a crucial role in quantum materials. Yet, there is no universal method that would simultaneously accurately account for strong electron-phonon interactions and electronic correlations. By combining methods of the variational quantum eigensolver and the variational non-Gaussian solver, we develop a hybrid quantum-classical algorithm suitable for this type of correlated systems. This hybrid method tackles systems with arbitrarily strong electron-phonon coupling without increasing the number of required qubits and quantum gates, as compared to purely electronic models. We benchmark the new method by applying it to the paradigmatic Hubbard-Holstein model at half filling, and show that it correctly captures the competition between charge density wave and antiferromagnetic phases, quantitatively consistent with exact diagonalization.

M. Bönitz