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Title: Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet

The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ~99% using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in the substrate. The coherence time measured using dynamical decoupling extends up to ~400 μs for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10-kHz to 1-MHz range, possibly because charge noise affects the spin via the micromagnet gradient. Furthermore, this work shows that an electron spin in an Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [2] ;  [4]
  1. QuTech, Delft (The Netherlands); Delft Univ. of Technology, Delft (The Netherlands)
  2. Univ. of Wisconsin-Madison, Madison, WI (United States)
  3. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  4. QuTech, Delft (The Netherlands); Delft Univ. of Technology, Delft (The Netherlands); Intel Corp., Hillsboro, OR (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0027-8424
Grant/Contract Number:
FG02-03ER46028; W911NF-12-0607; AC02-07CH11358; 319360; J1102
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 42; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States); Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
97 MATHEMATICS AND COMPUTING; 77 NANOSCIENCE AND NANOTECHNOLOGY; Si/SiGe quantum dot; qubit; dynamical decoupling; randomized benchmarking; electron spin
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1335026; OSTI ID: 1357022