Room-temperature coherence boosting of molecular graphenoids by environmental spectral decomposition

We explore the usage of pulse sequence optimization to boost the quantum properties of topological defects in molecular graphenoids at high temperatures. We reach spin-lattice relaxation times on the same order as those of the best quantum devices in the literature, ∼1 ms at room temperature. The coherence time is shown to be heavily affected by the hyperfine interaction and by the high concentration of hydrogen atoms in particular. We test and compare the applicability and performance of different decoupling sequences in enhancing the coherence, identifying the best-performing sequences for the purposes of robust state initialization and coherence optimization. Coherence times up to 30 𝜇⁢s are reached, and we provide insight into the system-environment interaction mechanisms, with a semiclassical model that considers the nuclear bath as a source of a classical random noise and the dynamical decoupling as a filter function. Full deconvolution of the noise spectrum of the bath is obtained, and we show the noise density has a Lorentzian shape whose parameters describe the nuclear-bath dynamics.