Coherent oscillations of correlations in fermionic Hubbard gases

Coherent oscillations in ultracold atoms, following by Hamiltonian quench, provide a unique pathway for investigating the off-diagonal coherence in strongly correlated quantum systems. While such nonequilibrium dynamics have been extensively studied in bosonic atoms and Bose-Fermi mixtures, investigations in a fermionic Hubbard gas have so far remained purely theoretical. Here, we observe collapse and revival of the interference patterns and sinusoidal oscillations of first-order correlations, induced by coherent doublon-hole pairs in fermionic Hubbard gases, following a sudden quench to a deep optical lattice. The oscillation frequency provides a precise calibration of the interaction energy. At half filling and intermediate interactions, we observe an inverted quasi-momentum distribution, with maximum occupation at the edge of the Brillouin zone associated with negative correlations. The observed coherent quench dynamics, originating from coherent doublon-hole pairs, exhibit clear distinctions from the collapse and revival of long-range bosonic superfluids. We systematically measure the doublon–hole correlation as functions of lattice filling and interaction strength, demonstrating that the coherent oscillations of the interference patterns serve as a novel probe of higher-order coherence, opening new avenues for exploring the nonequilibrium dynamics in many-body systems.