Exact ground state of the Lieb-Mattis Hamiltonian as a superposition of Néel states
Physical Review Research
We show that the exact ground state of the Lieb-Mattis Hamiltonian is an equal-weight superposition of all possible classical Néel states, and provide an exact formulation of this superposition in the z-spin basis for both S=1/2 and general S using Schwinger bosons. In general, a superposition of possible rotations on a general initial state is symmetric if and only if the initial state has a nonzero overlap with a singlet state and is otherwise made up of states that vanish due to the
... ation. Most notably, |s, m=0 〉 states will vanish if symmetrized, which explains how a superposition of Néel states projects onto its singlet component.