Efficient variational diagonalization of fully many-body localized Hamiltonians

Understand

We introduce a unitary matrix-product operator (UMPO) based variational method that approximately finds all the eigenstates of fully many-body localized (fMBL) one-dimensional Hamiltonians.

• The computational cost of the variational optimization scales linearly with system size for a fixed bond dimension of the UMPO ansatz.
• We demonstrate the usefulness of our approach by considering the Heisenberg chain in a strongly disordered magnetic field for which we compare the approximation to exact diagonalization results.