Optical control of nuclear spins in molecules points to new paths for quantum technologies

Karlsruher Institut für Technologie (KIT)

Nuclear magnetic resonance (NMR) is an established method for analyzing materials and molecules, with applications ranging from chemical analysis to quantum information processing. For a new paper, KIT researchers analyzed a molecular crystal containing europium ions. Such ions have especially narrow optical transitions that allow direct addressing of nuclear spin states. Using laser light, they were able to initialize nuclear spins in defined states and then read out those states.

In addition to optical addressing, the researchers used high-frequency fields to control the spins and protect them from interfering environmental influences. They achieved nuclear spin quantum coherence with a lifetime of up to two milliseconds, an interval during which a quantum system maintains a precisely defined quantum mechanical state.

Nuclear Spins as Stable Quantum Information Carriers

“The results show that molecular materials can be a promising platform for future quantum components,” said Professor David Hunger of the Physikalisches Institut at KIT. “A special advantage is that we can address the nuclear spins without interference from electron spins, making it possible to implement especially stable and dense qubit registers in the future.”

At KIT’s Institute for Quantum Materials and Technologies and Institute of Nanotechnology, a group of researchers headed by Professor Mario Ruben synthesized the molecular crystals and investigated their suitability for use in quantum platforms.

Tailored Molecules for Atomically Precise Qubit Registers

In the long term, optically addressable nuclear spins in molecules offer new prospects for the development of scalable quantum computers. Molecular systems can be chemically customizedtailored, potentially enabling atomically precise qubit registers. In addition, optically detected NMR facilitates the implementation of new high-resolution NMR methods that will allow detailed analysis of complex materials in the future.

The results of this research underscore the great potential of molecular systems for future quantum technologies and are an important step toward optically networked quantum processing systems.