Talking to molecular qubits: New physical pathways for spin readout and control

Molecular quantum bits (MQBs) combine long coherence times with unparalleled chemical tunability, making them compelling candidates for quantum technologies, specifically for computing, sensing and simulation. Despite decades of research and impressive quantum properties, a central challenge persists: how can we efficiently control and read out their spin state? Conventional routes, such as volume microwave resonators and, more recently, superconducting resonators or optical detection, either lack sensitivity or introduce significant experimental overheads. Importantly, no method has yet achieved practical electrical readout of MQBs, despite their potential for scalable device integration.

In this talk, I will outline emerging physical pathways that may enable such interactions. I will discuss how MQBs behave in electrically active environments, and how both electrical currents and pure spin currents could serve as sensitive probes of their spin dynamics. I will then introduce a complementary, material-agnostic approach based on self-oscillating microwave circuits, where the frequency of a microscale LC oscillator becomes a direct and sensitive reporter of spin susceptibility. Recent advances in oscillator-based EPR, quantitative field mapping, and chemical sensing illustrate the scientific reach of this paradigm.

Together, these directions point toward a new vision for hybrid quantum–spintronic architectures and new strategies for high-sensitivity MQB readout. I will conclude by outlining how these concepts could evolve toward addressing individual molecular spins and studying their interactions with complex quantum materials.