Quantum dots across Rome rooftops

A team led by Sapienza University of Rome, with partners in Germany, Austria and the Netherlands, teleported photon polarisation states between photons made by two different semiconductor quantum dots, tuned to match using strain and magnetic fields. Fidelity reached 82 ± 1% between two labs, and about 80 ± 4% when the output photon also crossed a 270 m free-space link between campus buildings. Published in Nature Communications.

Why it matters for teleportation

• Quantum dots can emit photons on demand, a likely building block for quantum relays.
• Shows two independent, mismatched light sources can still work together outdoors.
• Limitation: rates were very low (about 0.1 successful teleportations per second at the best fidelity) and relied on tight timing filters.