DEER measurements on molecular nanomagnet dimer spins separated by 1.3 GHz

Molecular systems hosting multiple effective electronic spins are promising candidates for a variety of applications including quantum computing. Effectively using these systems requires characterization not only of the individual spins but also of their coupling. Double electron-electron resonance (DEER) experiments are commonly used to measure such couplings, but require simultaneous excitation of each spin, which is difficult if the spin transition frequencies are separated by more than the bandwidth of a standard monomodal resonator. We have developed an electron spin resonance (ESR) spectrometer that incorporates custom-designed multi-modal loop-gap resonators to address both spins in a heterodimer of the molecular nanomagnet Cr₇Mn, where the spin frequencies are separated by 1.3 GHz. We will present our progress in performing DEER experiments to determine the coupling between the spins in the dimer. Once fully characterized, the coupling strength will be incorporated into schemes to perform multi-qubit gates in the heterodimer.