In quantum physics, linked photons can provide ultrasecure communication even if the link between them is lost.
Quantum communication, which physicists hope can thwart eavesdropping attempts, often relies on entanglement — tight links between the quantum states of two particles. However, that link is easily broken by background noise, making schemes difficult to implement in real-world situations. Zheshen Zhang and his team at the Massachusetts Institute of Technology in Cambridge showed that correlations between the light pulses exchanged by two parties over an optical fibre are strong enough to convey messages even if noise destroys the photons' entanglement.
This is the first experimental demonstration of a communication scheme with broken entanglement. The work also supports the idea that technologies using entanglement could be made to work even in practical situations.
About this article
Cite this article
Broken quantum links still work. Nature 499, 129 (2013). https://doi.org/10.1038/499129a