Topological phases, time reversal symmetry and flying qubits

Spintronics replaces electronics, by using both the charge and the spin of the electrons. Quantum computing is based on qubits. Here we discuss mobile (flying) electrons, which can carry such quantum information. Tuning this information involves electric and magnetic fields, which vary geometrical and topological phases on the related spinors. Although the spin-orbit interaction (which determines the Aharonov-Casher phase) is a major tool for such tuning, it is often not sufficient, because it conserves time-reversal symmetry. The talk will describe several ways to break this symmetry, both for a mesoscopic interferometer and for helical molecules.