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Title: 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 (30mT and above), the 29Si and 13C 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. Lastly, our results point to polyatomic crystals as promising hosts for coherent qubits in the solid state.
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1]
  1. The Univ. of Chicago, Chicago, IL (United States)
  2. The Univ. of Chicago, Chicago, IL (United States); IBM T.J. Watson Research Center, Yorktown Heights, NY (United States)
  3. The Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
University of Chicago - Materials Research Science & Engineering Center (MRSEC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences and Engineering Division; National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
Country of Publication:
United States
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; electronic structure; quantum physics; qubits; semiconductors
OSTI Identifier: