If we manage to keep pace with Moore's Law for a few more decades, the ultimate challenge would come at the level of a single atom, electron, or perhaps photon. At that scale, computing would be governed by quantum mechanics, an intimidating yet tantalizing prospect. Vastly more efficient than classical computing, which relies on logic gates that flip between two states, 1 or 0, quantum computing would have access to multiple quantum states, or qubits, at the same time. This would allow quantum computers to take on multiple calculations simultaneously instead of serially.

Traits that could be used as qubits include the different spins of electrons, the magnetic orientation of ions, or the photons emitted by ions. Researchers have already built the first solid-state quantum processor and a device, shown here, that uses lasers to manipulate the qubits of super-chilled beryllium ions.