Entangled matter the next big thing in qubits

Teleportation inches forward

Researchers at the Max Planck Institute are trumpeting as a breakthrough the successful teleportation of quantum information over 21 metres.

To be fair, however, the record they're claiming to have set is for “matter-matter teleportation” – rather than merely carrying a quantum state such as polarisation between a pair of entangled photons, their new research demonstrates entanglement between single atoms entrapped in optical cavities.

That's important, the researchers say, because trapped atoms offer at least a feasible path to quantum memory, compared to atoms in free space, which are the subject of most matter-matter entanglement experiments. By using the trapped atoms, the scientists hope they've identified a mechanism that's more scalable.

In this experiment, the scientists teleported the spin state of the atomic qubit in one node to the other. Entangled photons were used to map the states – at node A, the spin was mapped onto the photon's polarisation.

At the second node, an entanglement was generated beween a photon and a second trapped atom, and when a Bell state measurement is made of the two photons, the photons are destroyed and the second atom's state is projected onto the first atom.

The scheme only has an efficiency of 0.1 percent, but the researchers say this is 100,000 times higher than achieved in previous experiments.

Christian Nölleke, lead author of the paper to be published in Physical Review Letters, says “Future plans include to increase the light-matter interaction by using cavities that provide us with a higher atom-photon coupling strength. This would increase the efficiency of our protocol even further. Another prospect is to implement a different type of Bell-state measurement to increase the efficiency.”

The pre-press version of Nölleke's research is at Arxiv. ®

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