  The article surveys quantization schemes for metric graphs with spin.
Typically quantum graphs are defined with the Laplace or Schrodinger operator
which describe particles whose intrinsic angular momentum (spin) is zero.
However, in many applications, for example modeling an electron (which has
spin-1/2) on a network of thin wires, it is necessary to consider operators
which allow spin-orbit interaction. The article presents a review of
quantization schemes for graphs with three such Hamiltonian operators, the
Dirac, Pauli and Rashba Hamiltonians. Comparing results for the trace formula,
spectral statistics and spin-orbit localization on quantum graphs with spin
Hamiltonians.
