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Title: Two-axis control of a singlet-triplet qubit with an integrated micromagnet.

The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double-quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micromagnet, the magnetic field difference ΔB between the two sides of the double dot is large enough to enable the achievement of coherent rotation of the qubit’s Bloch vector around two different axes of the Bloch sphere. By measuring the decay of the quantum oscillations, the inhomogeneous spin coherence time T*2 is determined. By measuring T*2 at many different values of the exchange coupling J and at two different values of ΔB, we provide evidence that the micromagnet does not limit decoherence, with the dominant limits on T*2 arising from charge noise and from coupling to nuclear spins.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. Lancaster Univ. (United Kingdom)
Publication Date:
Report Number(s):
SAND-2015-5833J
Journal ID: ISSN 1091-6490; 618482
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 111; Journal Issue: 33; Journal ID: ISSN 1091-6490
Publisher:
National Academy of Sciences
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICS AND COMPUTING; semiconductor spin qubit; quantum nanoelectronics
OSTI Identifier:
1344459
Alternate Identifier(s):
OSTI ID: 1344470

Wu, Xian, Ward, D. R., Prance, J. R., Kim, Dohun, Gamble, John King, Mohr, Robert, Shi, Zhan, Savage, D. E., Lagally, M. G., Friesen, Mark, Coppersmith, S. N., and Eriksson, M. A.. Two-axis control of a singlet-triplet qubit with an integrated micromagnet.. United States: N. p., Web. doi:10.1073/pnas.1412230111.
Wu, Xian, Ward, D. R., Prance, J. R., Kim, Dohun, Gamble, John King, Mohr, Robert, Shi, Zhan, Savage, D. E., Lagally, M. G., Friesen, Mark, Coppersmith, S. N., & Eriksson, M. A.. Two-axis control of a singlet-triplet qubit with an integrated micromagnet.. United States. doi:10.1073/pnas.1412230111.
Wu, Xian, Ward, D. R., Prance, J. R., Kim, Dohun, Gamble, John King, Mohr, Robert, Shi, Zhan, Savage, D. E., Lagally, M. G., Friesen, Mark, Coppersmith, S. N., and Eriksson, M. A.. 2014. "Two-axis control of a singlet-triplet qubit with an integrated micromagnet.". United States. doi:10.1073/pnas.1412230111. https://www.osti.gov/servlets/purl/1344459.
@article{osti_1344459,
title = {Two-axis control of a singlet-triplet qubit with an integrated micromagnet.},
author = {Wu, Xian and Ward, D. R. and Prance, J. R. and Kim, Dohun and Gamble, John King and Mohr, Robert and Shi, Zhan and Savage, D. E. and Lagally, M. G. and Friesen, Mark and Coppersmith, S. N. and Eriksson, M. A.},
abstractNote = {The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double-quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micromagnet, the magnetic field difference ΔB between the two sides of the double dot is large enough to enable the achievement of coherent rotation of the qubit’s Bloch vector around two different axes of the Bloch sphere. By measuring the decay of the quantum oscillations, the inhomogeneous spin coherence time T*2 is determined. By measuring T*2 at many different values of the exchange coupling J and at two different values of ΔB, we provide evidence that the micromagnet does not limit decoherence, with the dominant limits on T*2 arising from charge noise and from coupling to nuclear spins.},
doi = {10.1073/pnas.1412230111},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 33,
volume = 111,
place = {United States},
year = {2014},
month = {8}
}