Graphene quantum dots are promising candidates for qubits due to weak
spin-orbit and hyperfine interactions. The hyperfine interaction, controllable
via isotopic purification, could be the key to further improving the coherence.
Here, we use isotopically enriched graphite crystals of both 12C and
13C grown by high-pressure-high-temperature method to exfoliate graphene
layers. We fabricated Hall bar devices and performed quantum transport
measurements, revealing mobilities exceeding 105cm2/Vs and a
long mean free path of microns, which are as high as natural graphene.
Shubnikov-de Haas oscillations, quantum Hall effect up to the filling factor of
one, and Brown-Zak oscillations due to the alignment of hBN and graphene are
observed thanks to the high mobility. These results constitute a material
platform for physics and engineering of isotopically-enriched graphene qubits.Comment: 6 pages, 2 figure