The basic steps of quantum information processing are relatively straightforward, at least on paper: Prepare qubits in an appropriate initial state, let them evolve under the influence of one- and two-qubit gate operations, and read out the results. But obtaining scalable physical implementations of these steps continues to challenge researchers, in part because of the conflicting requirements of ensuring sufficient isolation from the environment to maintain qubit coherence and allowing sufficient coupling between qubits to enable the requisite two-qubit operations.
Spins in semiconductors have many desirable properties that make them candidates for quantum information implementations. 1 The spins can have very long coherence times, and an extensive repertoire of fabrication expertise, amassed over decades, can be exploited for sample preparation. Such properties have also raised hopes for spintronics—exploiting the spin degree of freedom in addition to the charge degree of freedom in electronic circuits. Spintronics, too, will require the ability...
