Europium and light: An innovative platform for quantum computers and communications
(Phys.org) A team of scientists from the French National Centre for Scientific Research (CNRS ) and l’Université de Strasbourg, with support from Chimie ParisTech-PSL and in collaboration with German teams from KIT, has successfully demonstrated the value of europium molecular crystals for quantum communications and processors, thanks to their ultra-narrow optical transitions enabling optimal interactions with light.
These crystals are the combined product of two systems already used in quantum technology: rare earth ions (such as europium), and molecular systems. Rare-earth crystals are known for their excellent optical and spin properties, but their integration in photonic devices is complex. Molecular systems generally lack spins (a storage or computing unit) or—on the contrary—present optical lines that are too broad to establish a reliable link between spins and light.
Europium molecular crystals represent a major advance, as they have ultra-narrow linewidths. This translates into long-lived quantum states, which were used to demonstrate the storage of a light pulse inside these molecular crystals. Moreover, a first building block for a quantum computer controlled by light has been obtained. This new material for quantum technologies offers previously unseen properties, and paves the way for new architectures for computers and quantum memories in which light will play a central role.
The results also open broad prospects for research thanks to the many molecular compounds that can be synthesized.