Fig. 2: Comparison of the coherence time and unpaired electron spins between an O-terminated diamond and graphene-diamond heterojunction.
From: Enhancement of quantum coherence in solid-state qubits via interface engineering
a Hahn-echo decay curves from the same NV center. The Hahn-echo coherence time T2 is improved ~3-fold after graphene patching. b Summary of the Hahn-echo coherence time T2 enhancement of all 20 shallow NVs after graphene patching. They are arranged in ascending order of the T2 before enhancement. Error bars represent the fitting uncertainty. c DEER spectroscopy detected by NV5. Blue dots denote the surface unpaired electron signals resonated at ω = γeB = 798 MHz, where C is the contrast. The surface unpaired electron spins signal disappears after graphene patching, denoted by red dots. The red and blue curves are offset for clarity.
