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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.
Authors:
 [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):
IS-J-9131
Journal ID: ISSN 0027-8424
Grant/Contract Number:
FG02-03ER46028; W911NF-12-0607; AC02-07CH11358; 319360; J1102
Type:
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
Publisher:
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
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; 77 NANOSCIENCE AND NANOTECHNOLOGY; Si/SiGe quantum dot; qubit; dynamical decoupling; randomized benchmarking; electron spin
OSTI Identifier:
1328496
Alternate Identifier(s):
OSTI ID: 1335026; OSTI ID: 1357022

Kawakami, Erika, Jullien, Thibaut, Scarlino, Pasquale, Ward, Daniel R., Savage, Donald E., Lagally, Max G., Dobrovitski, Viatcheslav V., Friesen, Mark, Coppersmith, Susan N., Eriksson, Mark A., and Vandersypen, Lieven M. K.. Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet. United States: N. p., Web. doi:10.1073/pnas.1603251113.
Kawakami, Erika, Jullien, Thibaut, Scarlino, Pasquale, Ward, Daniel R., Savage, Donald E., Lagally, Max G., Dobrovitski, Viatcheslav V., Friesen, Mark, Coppersmith, Susan N., Eriksson, Mark A., & Vandersypen, Lieven M. K.. Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet. United States. doi:10.1073/pnas.1603251113.
Kawakami, Erika, Jullien, Thibaut, Scarlino, Pasquale, Ward, Daniel R., Savage, Donald E., Lagally, Max G., Dobrovitski, Viatcheslav V., Friesen, Mark, Coppersmith, Susan N., Eriksson, Mark A., and Vandersypen, Lieven M. K.. 2016. "Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet". United States. doi:10.1073/pnas.1603251113.
@article{osti_1328496,
title = {Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet},
author = {Kawakami, Erika and Jullien, Thibaut and Scarlino, Pasquale and Ward, Daniel R. and Savage, Donald E. and Lagally, Max G. and Dobrovitski, Viatcheslav V. and Friesen, Mark and Coppersmith, Susan N. and Eriksson, Mark A. and Vandersypen, Lieven M. K.},
abstractNote = {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.},
doi = {10.1073/pnas.1603251113},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 42,
volume = 113,
place = {United States},
year = {2016},
month = {10}
}