  An effective spin concept is introduced to examine the mathematical and
physical analogy between phase coherent charge transport in mesoscopic systems
and quantum operations on spin based qubits. When coupled with the Bloch sphere
concept, this isomorphism allows formulation of transport problems in a
language more familiar to researchers in the field of spintronics and quantum
computing. We exemplify the synergy between charge tunneling and spin qubit
unitary operations by recasting well-known problems of tunneling through a
delta scatterer, a resonant tunneling structure, a superlattice structure, and
arrays of elastic scatterers, in terms of specific unitary operations
(rotations) of a spinor on the Bloch sphere.
