Superconducting qubits, developed for quantum computing, can also serve as sensitive detectors for probing the magnetic properties of individual molecules. The Quantronics group has demonstrated the detection of individual electron spins in crystals by counting the microwave photons they emit with a transmon qubit [1], as well as the coherent control of neighbouring nuclear spins [2]. This internship will contribute to our ongoing work on molecular spins in frozen solution, with the aim of performing magnetic resonance spectroscopy on individual spin-labelled biomolecules. Electron spin resonance (ESR) provides information about the local electronic and magnetic environment of molecules. In structural biology, interactions between spin labels can also be used to measure distances within proteins. Conventional experiments average over many molecules, obscuring their individual properties and limiting spectroscopic resolution. Measuring molecules individually could overcome this ensemble broadening and reveal local environments and spin couplings that are otherwise unresolved, opening access to more detailed structural information.