QUROPE Quantum Information Processing and Communication in Europe

In a recent publication in Nature Physics the group led by SOLID partner Ronald Hanson realized a two-qubit parity measurement on nuclear spins localized near a nitrogen-vacancy centre in diamond by exploiting an electron spin as a readout ancilla. The measurement enabled the group to project the initially uncorrelated nuclear spins into maximally entangled states. By combining this entanglement with single-shot readout we demonstrate the first violation of Bell’s inequality with solid-state spins. The results reported in the paper introduce a new class of experiments in which projective measurements create, protect and manipulate entanglement between solid-state qubits.