Swiss scientists find the key to quantum memory: they have discovered that the ytterbium, a chemical element of the periodic table, subjected to precise magnetic fields, is able to isolate itself from the environment and operate at high frequencies, thus allowing it to store and replicate the quantum signal quickly and build a global quantum network.
The ytterbium, a rare earth discovered in 1878 that is part of the periodic table of elements, can become the star of quantum communication because researchers at the University of Geneva have discovered that its characteristics allow the quantum signal to be stored and replicated with much speed and integrity.
This finding, published in Nature Materials, could establish the bases of a global quantum network, according to the researchers, since the ytterbium is not only capable of storing and protecting the fragile quantum information, but also of operating at the same time at high frequencies.
These characteristics make the ytterbium the ideal candidate for future quantum networks, whose objective is to propagate the signal (information) over long distances through safe quantum repeaters. One of the current challenges of quantum communication, which represents the future of the secure exchange of information through networks, consists of creating memories capable of storing the quantum information transported by light (photons).
For this reason, scientists focus on the production of quantum memories capable of repeating the signal by capturing photons and synchronizing them with each other, in order to spread them further and further away. What was missing was the right material to make these quantum memories.
The idea is to find a material well isolated from environmental disturbances, but at the same time capable of operating at high frequencies (which allow to store and restore the photon quickly), two characteristics that are normally incompatible. Although at present there are prototypes of quantum memory tested in the laboratory, mainly based on other rare earths such as europium or praseodymium, its speed, however, is still not very high.
Researchers have discovered that by subjecting the ytterbium to precise magnetic fields, it enters a state of insensibility that disconnects it from environmental perturbations and allows the photon to be trapped in order to synchronize it.
Simultaneous coherence enhancement of optical and microwave transitions in solid-state electronic spins. Antonio Ortu et al. Nature Materials, volume 17, pages671–675 (2018). DOI :https://doi.org/10.1038/s41563-018-0138-x