  We explore potentials that break time-reversal symmetry to confine the
surface states of 3D topological insulators into quantum wires and quantum
dots. A magnetic domain wall on a ferromagnet insulator cap layer provides
interfacial states predicted to show the quantum anomalous Hall effect (QAHE).
Here we show that confinement can also occur at magnetic domain
heterostructures, with states extended in the inner domain, as well as
interfacial QAHE states at the surrounding domain walls. The proposed geometry
allows the isolation of the wire and dot from spurious circumventing surface
states. For the quantum dots we find that highly spin-polarized quantized QAHE
states at the dot edge constitute a promising candidate for quantum computing
qubits.
