Can quantum entanglement end the internet

Viennese researchers achieved more robust quantum entanglement

The phenomenon of quantum entanglement, which runs counter to everyday understanding, promises new possibilities in the transmission of information. One problem with this, however, is the great susceptibility of quantum networks to external interference. Even a slight interaction with the environment can destroy the entanglement. Viennese physicists have now succeeded in making quantum entanglement more robust.

The quantum physical entanglement makes it possible for two particles - such as photons - to remain connected to one another as if by magic. The measurement on one directly determines the condition of the other, even if they are as far apart as you want. If, for example, the direction of light oscillation (polarization) is measured on an entangled photon, the partner particle will instantly also oscillate in the same direction.

Difficult shielding

This amazing property gives hope for a wide range of technical applications. Considerations and initial solutions for quantum networks, where information between communication partners in laboratory experiments or even between satellites and ground stations are exchanged by means of entangled light particles, are relatively far advanced. Approaches to transferring information on this basis could in the future also lead to a kind of quantum internet - something scientists from the Institute for Quantum Optics and Quantum Information (IQOQI) Vienna of the Austrian Academy of Sciences (ÖAW) are working on.

In the laboratory environment, it is relatively easy to shield the sensitive quantum systems from interference, but outside of this it is sometimes quite difficult to transmit data, where the noise feared by the researchers increases significantly. Especially in the presence of many other photons - in daylight - the entanglement can be destroyed quickly.

High-dimensional entanglement

The Viennese physicists from IQOQI around Marcus Huber and the first author of the work published in the journal "Physical Review X", Sebastian Ecker, have now made the entanglement more complex. While the polarization and the time at which the photons were generated served as information carriers so far, the team has now been able to incorporate a further level into the quantum system with the generation location.

With this higher-dimensional entanglement, the susceptibility to disturbances can be significantly reduced, as the scientists have shown. Under these conditions, the special properties of the variously entangled photons could still be clearly differentiated from the environment even with strong background noise, says Huber.

This means that quantum transmission can now also be shifted from night to day. "Quantum entanglement is the backbone of quantum communication," says Ecker. "There can only be a secure quantum Internet if the entanglement is transmitted largely undisturbed. With our experiment, we were able to show how the entanglement can be made more robust." (red, APA, November 30, 2019)