(PhysicsWorld) Christopher Ballance and colleagues at Oxford University have shown how to link trapped ions by entangling them using the photons they emit when excited by a laser beam. This technique was first realized by Chris Monroe and colleagues at the University of Maryland in the US, and now the Oxford group has boosted both the rate and fidelity of the entanglement by collecting more of the photons given off by the ions and by limiting imperfections in the emission process. The team says that their scheme paves the way to scalable quantum computers made from multiple ion traps that are linked to one another via photonic interconnects. Trapped ions offer a way of generating qubits with very low levels of noise, and therefore maintain the quantum coherence that is required to perform calculations.
Trapped Ions ‘Good Progress on Way to Real-World Applications’
Rainer Blatt works on trapped ions at the University of Innsbruck in Austria and describes the latest work as “a nice technical achievement” that provides “good progress on the way to real-world applications”. But he cautions that in future the technique will have to be applied in the presence of more ions, perhaps to link two quantum computer nodes or to develop a quantum repeater. “There will be certainly more technological problems before such devices are readily available,” he says.

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