Charge-4e Superconductivity in a Hubbard model

University of Zurich

A phase of matter in which fermion ‘quartets’ form a superconducting condensate, rather than paradigmatic Cooper pairs, is a recurrent subject of experimental and theoretical studies. However, a comprehensive microscopic understanding of charge-4e superconductivity as a quantum phase is lacking. Here, we propose and study a one-dimensional two-orbital tight-binding model with Hubbard interactions. Using density matrix renormalization group calculations, we show that the model supports charge-4e superfluidity, and that this phase can be stabilized well beyond the perturbative regime. Furthermore, we demonstrate that 4e-condensation dominates over 2e-condensation even for almost decoupled chains, a suitable scenario for experiments with ultracold atoms.