  Transport properties in mesoscopic networks are investigated, where the
strength of the (Rashba-type) spin-orbit coupling is assumed to be tuned with
external gate voltages. We analyze in detail to what extent the ideal behavior
and functionality of some promising network-based devices are modified by
random (spin-dependent) scattering events and by thermal fluctuations. It is
found that although the functionality of these devices is obviously based on
the quantum coherence of the transmitted electrons, there is a certain
stability: moderate level of errors can be tolerated. For mesoscopic networks
made of typical semiconductor materials, even cryogenic temperatures can smear
out the desired transport properties. When the energy distribution of the input
carriers is narrow enough, it turns out that the devices can operate close to
their ideal limits even at relative high temperature. As an example, we present
results for two different networks: one that realizes a Stern-Gerlach device
and another that simulates a spin quantum walker. Finally we propose a simple
network that can act as a narrow band energy filter even in the presence of
random scatterers.
