  We use a superspin Hamiltonian defined on an infinite-dimensional Fock space
with positive definite scalar product to study localization and delocalization
of noninteracting spinless quasiparticles in quasi-one-dimensional quantum
wires perturbed by weak quenched disorder. Past works using this approach have
considered a single chain. Here, we extend the formalism to treat a
quasi-one-dimensional system: a quantum wire with an arbitrary number of
channels coupled by random hopping amplitudes. The computations are carried out
explicitly for the case of a chiral quasi-one-dimensional wire with broken
time-reversal symmetry (chiral-unitary symmetry class). By treating the space
direction along the chains as imaginary time, the effects of the disorder are
encoded in the time evolution induced by a single site superspin
(non-Hermitian) Hamiltonian. We obtain the density of states near the band
center of an infinitely long quantum wire. Our results agree with those based
on the Dorokhov-Mello-Pereyra-Kumar equation for the chiral-unitary symmetry
class.
