Reconstructing entanglement Hamiltonian via entanglement eigenstates

Entanglement-based measurements have proven to be beneficial in analyzing strong correlation effects in condensed matter systems. While diagnostics such as entanglement entropy and spectrum are numerically straightforward to obtain and thus widely used, the physically more illuminating object that the entanglement Hamiltonian is remains elusive, since its determination involves the daunting task of fully diagonalizing a many-body reduced density matrix. Here, the authors show how to circumvent this technical challenge and construct the entanglement Hamiltonian from a single entanglement eigenstate.