Scientists at Argonne National Laboratory and the University of Chicago have developed an advanced computer modeling method that enables accurate prediction and fine-tuning of key magnetic properties of molecular qubits, a crucial component in quantum technology.
Quantum information technology promises powerful future applications, including next-generation computers and sensitive detectors in medicine and navigation. Central to these technologies are qubits, the fundamental units of quantum information, whose reliability and longevity are essential for practical use.
The research team focused on molecular qubits based on chromium-centered molecules embedded within crystals. Traditionally, molecular qubit design has relied on experimental trial and error, building different materials and testing their performance. The new computational method offers a predictive approach, providing design rules to engineer qubit properties suited to specific applications such as quantum communication, sensing, or computing.
A key feature of these molecular qubits is “spin,” which encodes quantum information by splitting into three magnetic energy levels through a phenomenon called zero-field splitting (ZFS). Controlling ZFS is vital for precise qubit manipulation and for extending qubit coherence times—the duration qubits can retain information. The new modeling technique allows prediction of these ZFS values and coherence times, effectively offering a way to design qubits with improved stability.
The researchers identified two primary factors influencing ZFS tuning: the geometry of the crystal environment around the chromium center and the electric fields generated by the crystal’s chemical composition. Their work is the first to provide a computational method that not only accurately predicts ZFS in these molecular qubits but also reveals how electric fields within the host crystal can be manipulated to control spin properties.
This multidisciplinary effort, led by University of Chicago Professor Giulia Galli, included chemists, materials scientists, and physicists. Their findings, published in the Journal of the American Chemical Society, align closely with experimental results, validating the modeling approach.
The work was supported by Q-NEXT, a U.S. Department of Energy National Quantum Information Science Research Center led by Argonne National Laboratory. The researchers emphasized that this advance opens new avenues for the computational design of molecular qubits and sets the stage for further investigations into assembling qubits with tailored properties.