Synopsis: One Photon Good, Two Better

Although several powerful quantum algorithms have been put forth for quantum computing, implementing them in a physical device requires suitable qubits, protection from decoherence, and ways to read inputs and write outputs. Nitrogen-vacancy centers (NV) in diamond, which are nitrogen atoms coupled to a lattice vacancy, have pushed to the front of the queue of candidate qubits owing to their easily controllable spin states and stable optical properties. The trick now is to find a way to entangle and manipulate pairs of distant qubits for quantum computations.