Quantum decoherence dynamics of divacancy spins in silicon carbide.
Long coherence times are key to the performance of quantum bits (qubits). Here, we experimentally and theoretically show that the Hahn-echo coherence time of electron spins associated with divacancy defects in 4H-SiC reaches 1.3 ms, one of the longest Hahn-echo coherence times of an electron spin in a naturally isotopic crystal. Using a first-principles microscopic quantum-bath model, we find that two factors determine the unusually robust coherence. First, in the presence of moderate magnetic fields (30 mT and above), the29Si and13C paramagnetic nuclear spin baths are decoupled. In addition, because SiC is a binary crystal, homo-nuclear spin pairs are both diluted and forbidden from forming strongly coupled, nearest-neighbour spin pairs. Longer neighbour distances result in fewer nuclear spin flip-flops, a less fluctuating intra-crystalline magnetic environment, and thus a longer coherence time. Our results point to polyatomic crystals as promising hosts for coherent qubits in the solid state.
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.
Hosung
H
Seo
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.|IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA.
Abram L
AL
Falk
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.
Paul V
PV
Klimov
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.
Kevin C
KC
Miao
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.|Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.
Giulia
G
Galli
The Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60615, USA.
David D
DD
Awschalom
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