Ground and Excited-State Spectra of the Extended Fermi-Hubbard Model on IBM Heron v2 using the SqDRIFT Algorithm

We investigate the ground and excited-state energy spectra of the extended Fermi–Hubbard model for one-dimensional linear chains and two-dimensional clusters using IBM's Heron v2 quantum computer. The computational method employed is the recently introduced SqDRIFT algorithm, which combines sample-based Krylov quantum diagonalization (SKQD) with the qDRIFT randomized compilation of the Hamiltonian propagator. We compare the experimentally obtained spectra to numerically exact classical simulations, while also evaluating the roles of system size, device noise, and circuit depth on the algorithm's accuracy. These results provide a first demonstration of the SqDRIFT algorithm applied to strongly correlated lattice models, establishing its viability for studying complex quantum many-body physics in the pre-fault-tolerant quantum computing era.