Scientists unlock nitrogen-doped graphene for quantum computing breakthroughs

Scientists have developed a new method for creating and studying aza-triangulene, a nitrogen-doped graphene structure with unique electronic and magnetic properties. The breakthrough could pave the way for molecular-scale quantum computing components. By engineering frustrated antiferromagnetic systems, the team demonstrated a key step toward building multi-qubit quantum registers.

The research began with polyether-tethered azatriphenylene derivatives, modified with bromoalkyl chains at the 2,6,10-positions. Using Friedel-Crafts cyclization, the team treated these molecules with AlCl₃ in dichloromethane to form the central aromatic core of aza-triangulene precursors. This process generated triangulene-like macrocycles, which were then analysed on a gold surface.

Bond-resolved atomic force microscopy and scanning tunneling microscopy confirmed the successful formation of aza-triangulene and related structures. Low-bias tunneling spectroscopy revealed narrow spectral peaks, linked to the Kondo effect with temperatures around 3 K. These features indicated inelastic spin excitations and delocalised Kondo resonances across the molecular platform. To explore magnetic properties, the team extended a single-radical molecule with anthene units. This modification created a correlated spin system with a spin-1/2 ground state, verified under applied magnetic fields. Theoretical modelling, using density functional theory and multireference configuration interaction, further supported the observations. The introduction of nitrogen atoms into the graphene framework altered its electronic behaviour, inducing magnetism and spin-polarized arrangements. By engineering a frustrated antiferromagnetic triradical within the aza-triangulene architecture, the researchers demonstrated a potential building block for quantum information storage.

The study provides a clear method for synthesising and characterising aza-triangulene platforms. Its magnetic and electronic properties, including the Kondo effect and spin correlations, offer a foundation for developing molecular quantum registers. These findings bring scientists closer to realising scalable quantum computing components at the nanoscale.