Compute ground energy and state at a specified particle number.

Assumes the Jordan-Wigner transform. The input operator should be Hermitian and particle-number-conserving.

sparse_operator sparse

A Jordan-Wigner encoded sparse matrix.

particle_number int

The particle number at which to compute the ground energy and states

ground_energy float

The lowest eigenvalue of sparse_operator within the eigenspace of the number operator corresponding to particle_number.

ground_state ndarray

The ground state at the particle number