Putting a new spin on quantum-dot qubits

Realizing the potential of quantum computing requires finding viable ways to store and manipulate representations of the binary bits, 0 and 1. The many two-level quantum systems being explored for such qubits include not only the up and down spins of trapped atoms or ions and the polarized states of photons, but also the quantum states of superconducting Josephson junctions and electron spins trapped in quantum dots. A quantum dot is a nanostructure that confines a conduction-band electron in three spatial dimensions. © 2011 American Institute of Physics.