Quantum computing relies on the ability to store and manipulate qubits (superpositions of 1 and 0), but this is not easy to do without losing coherence. Now, Mikhail Lukin and colleagues from Harvard University, Stuttgart University and Texas A&M University have made a huge breakthrough. Using optical and microwave manipulation of electron and nuclear spins associated with a nitrogen vacancy in diamonds, they have succeeded in creating a controllable quantum register.
Using the spins to store qubits and transfer them without loss of coherence even at room temperature, the team got them to interact coherently, having made use of the coupling between the nitrogen-vacancy spin system and the nuclear spins of nearby carbon-13 nuclei, which naturally make up 1.1% of a diamond. Their observations indicate that when advanced nuclear magnetic resonance techniques are used, controlled manipulation of a few coupled nuclear spin qubits is possible with coherence times that can approach seconds. These registers could be used as a basis for scalable, optically coupled quantum information systems.