The concept of effective spin is introduced to underpin the fundamental isomorphism between two apparently disparate fields of physics—phase coherent charge transport in mesoscopic systems and qubit operations in a spin-based quantum logic gate. Together with the Bloch sphere concept, this isomorphism allows transport problems to be formulated in a language more familiar to workers in spintronics and quantum computing. We exemplify the application of the effective spin concept by formulating several charge transport problems in terms of specific unitary operations (rotations) of a spinor on the Bloch sphere.
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