Processing quantum information in diamond

Quantum computing is an attractive and multidisciplinary field, which became a focus for experimental and theoretical research during the last decade. Among other systems, such as ions in traps and superconducting circuits, solid state based qubits are considered to be promising candidates for use in first experimental tests of quantum hardware. Here we report recent progress in quantum information processing with point defects in diamond. Qubits are defined as single spin states (electron or nuclear). This allows exploration of long coherence times (up to seconds for nuclear spins at cryogenic temperatures). In addition, the optical transition between ground and excited electronic states allows coupling of spin degrees of freedom to the state of the electromagnetic field. Such coupling gives access to spin state read-out via spin-selective scattering of photons. This also allows the use of spin states as robust memory for flying qubits (photons).