Scientists at Argonne National Laboratory and the University of Chicago have developed a new computational method to predict and engineer key magnetic properties of molecular qubits, representing a significant step toward improving quantum technologies.
A qubit, the fundamental information unit of quantum devices, underpins emerging capacities in computing and sensing expected to impact medicine, navigation, and other fields. Reliable and long-lasting qubits are essential to realize these technologies. Using advanced computer simulations, the research team focused on chromium-based molecular qubits—molecules embedded within larger crystals—to accurately predict key magnetic features, specifically the “zero-field splitting” (ZFS), which involves the splitting of spin energy levels crucial for encoding quantum information.
The team’s computational approach identifies how material properties, such as crystal geometry and electric fields generated by the crystal’s chemical composition, affect the tuning of ZFS and thus the coherence time, or longevity, of qubits. Their predictions correspond closely with experimental observations, marking the first instance in which ZFS in chromium molecular qubits has been reliably predicted and manipulated via computational methods.
Led by University of Chicago Professor Giulia Galli, a senior scientist at Argonne and a faculty member in the Pritzker School of Molecular Engineering and Department of Chemistry, the study offers new design rules to actively engineer qubit properties by adjusting the qubit’s surrounding environment. The research underscores the advantages of molecular qubits’ tunability compared to other types such as diamond-based qubits, enabling tailored design for specific quantum applications like communication, sensing, or computing.
The work, published in the Journal of the American Chemical Society and supported by the Department of Energy’s Q-NEXT National Quantum Information Science Research Center, benefited from interdisciplinary collaboration among chemists, materials scientists, and physicists. Postdoctoral researcher Michael Toriyama and graduate student Lorenzo Baldinelli were key contributors, emphasizing how computational tools developed over years enabled this advance.
This breakthrough offers a computational foundation for designing molecular qubits with precise, predictable properties and longer coherence times, which may accelerate progress toward scalable quantum technologies.