Eigenstate thermalization in the two-dimensional transverse field Ising model

Understand

We study the onset of eigenstate thermalization in the two-dimensional transverse field Ising model (2D-TFIM) in the square lattice.

• We consider two non-equivalent Hamiltonians: the ferromagnetic 2D-TFIM and the antiferromagnetic 2D-TFIM in the presence of a uniform longitudinal field.
• We use full exact diagonalization to examine the behavior of quantum chaos indicators and of the diagonal matrix elements of operators of interest in the eigenstates of the Hamiltonian.
• A finite size scaling analysis reveals that quantum chaos and eigenstate thermalization occur in those systems whenever the fields are nonvanishing and not too large.