A clock transition in the cr7mn molecular nanomagnet

Abstract

A viable qubit must have a long coherence time T2 . In molecular nanomagnets, T2 is often limited at low temperatures by the presence of dipole and hyperfine interactions, which are often mitigated through sample dilution, chemical engineering and isotope substitution in synthesis. Atomic-clock transitions offer another route to reducing decoherence from environmental fields by reducing the effective susceptibility of the working transition to field fluctuations. The Cr7Mn molecular nanomagnet, a heterometallic ring, features a clock transition at zero field. Both continuous-wave and spin-echo electron-spin resonance experiments on Cr7Mn samples, diluted via co-crystallization, show evidence of the effects of the clock transition with a maximum T2 ∼ 390 ns at 1.8 K. We discuss improvements to the experiment that may increase T2 further.