Improved Approximations for Extremal Eigenvalues of Sparse Hamiltonians

Daniel Hothem, Ojas Parekh, Kevin Thompson

We give a classical $1/(qk+1)$-approximation for the maximum eigenvalue of a $k$-sparse fermionic Hamiltonian with strictly $q$-local terms, as well as a $1/(4k+1)$-approximation w…