(Phys.org) Quantum physics could become the guarantor of secure information technology. To achieve this, individual particles of light—photons—are used for secure transmission of data. Findings by physicists from the Max Planck Institute for Solid State Research could play a key role. The researchers accidentally came across a light source that generates a photon pair from the energy of an electron. One of these particles of light has the potential to serve as a carrier of the fragile quantum information, the other, as a messenger to provide prior notification of its twin.
Researchers announced their discovery of an unexpected source of such photon pairs: a scanning tunnelling microscope. “According to theory, the probability of a photon pair forming is so low that we should never see it,” explains scientist Christopher Leon. “But our experiment shows that photon pairs are being generated at a much higher rate. That was a huge surprise for us.”
Quantum objects change their state when they are observed, i.e. measured. In quantum communication, this makes it difficult to control the information transmitted by photons. Just how do you guarantee a photon is on its way without measuring it? Pairs of photons are the solution. One photon might be able to serve as a messenger for its twin.
The findings open up new applications in photonics and quantum communication for tunnelling junctions.

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