Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. Although this is also possible in other materials, silicon-based systems have the advantage of interacting more weakly with nuclear spins. Reducing such interactions is important for the control of spin quantum bits because nuclear fluctuations limit quantum phase coherence, as seen in recent experiments in GaAs-based quantum dots1,2. Advances in reducing nuclear decoherence effects by means of complex control3,4,5 still result in coherence times much shorter than those seen in experiments on large ensembles of impurity-bound electrons in bulk silicon crystals6,7. Here we report coherent control of electron spins in two coupled quantum dots in an undoped Si/SiGe heterostructure and show that this system has a nuclei-induced dephasing time of 360 nanoseconds, which is an increase by nearly two orders of magnitude over similar measurements in GaAs-based quantum dots. The degree of phase coherence observed, combined with fast, gated electrical initialization, read-out and control, should motivate future development of silicon-based quantum information processors.
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Petta, J. R. et al. Coherent manipulation of coupled electron spins in semiconductor quantum dots. Science 309, 2180–2184 (2005)
Koppens, F. H. L., Nowack, K. C. & Vandersypen, L. M. K. Spin echo of a single electron spin in a quantum dot. Phys. Rev. Lett. 100, 236802 (2008)
Reilly, D. J. et al. Suppressing spin qubit dephasing by nuclear state preparation. Science 321, 817–821 (2008)
Barthel, C., Medford, J., Marcus, C. M., Hanson, M. P. & Gossard, A. C. Interlaced dynamical decoupling and coherent operation of a singlet-triplet qubit. Phys. Rev. Lett. 105, 266808 (2010)
Bluhm, H. et al. Dephasing time of GaAs electron-spin qubits coupled to a nuclear bath exceeding 200 μs. Nature Phys. 7, 109–113 (2011)
Simmons, S. et al. Entanglement in a solid-state spin ensemble. Nature 470, 69–72 (2011)
Tyryshkin, A. M. et al. Electron spin coherence exceeding seconds in high purity silicon. Nature Mater . (in the press); preprint at 〈http://arxiv.org/abs/1105.3772〉 (2011)
Ladd, T. D. et al. Quantum computers. Nature 464, 45–53 (2010)
Kane, B. E. A silicon-based nuclear spin quantum computer. Nature 393, 133–137 (1998)
Eriksson, M. A. et al. Spin-based quantum dot quantum computing in silicon. Quantum Inf. Process. 3, 133–146 (2004)
Borselli, M. G. et al. Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots. Appl. Phys. Lett. 99, 063109 (2011)
Goswami, S. et al. Controllable valley splitting in silicon quantum devices. Nature Phys. 3, 41–45 (2007)
Xiao, M., House, M. G. & Jiang, H. W. Parallel spin filling and energy spectroscopy in few-electron Si metal-on-semiconductor-based quantum dots. Appl. Phys. Lett. 97, 032103 (2010)
Borselli, M. G. et al. Measurement of valley splitting in high-symmetry Si/SiGe quantum dots. Appl. Phys. Lett. 98, 123118 (2011)
Lai, N. S. et al. Pauli spin blockade in a highly tunable silicon double quantum dot. Sci. Rep. 1, 110 (2011)
Hayes, R. R. et al. Lifetime measurements (T1) of electron spins in Si/SiGe quantum dots. Preprint at 〈http://arxiv.org/abs/0908.0173〉 (2009)
Xiao, M., House, M. G. & Jiang, H. W. Measurement of the spin relaxation time of single electrons in a silicon metal-oxide-semiconductor-based quantum dot. Phys. Rev. Lett. 104, 096801 (2010)
Morello, A. et al. Single-shot readout of an electron spin in silicon. Nature 467, 687–691 (2010)
Simmons, C. B. et al. Tunable spin loading and T 1 of a silicon spin qubit measured by single-shot readout. Phys. Rev. Lett. 106, 156804 (2011)
Johnson, A. C. et al. Triplet–singlet spin relaxation via nuclei in a double quantum dot. Nature 435, 925–928 (2005)
Liu, H. W. et al. Pauli-spin-blockade transport through a silicon double quantum dot. Phys. Rev. B 77, 073310 (2008)
Shaji, N. et al. Spin blockade and lifetime-enhanced transport in a few-electron Si/SiGe double quantum dot. Nature Phys. 4, 540–544 (2008)
Laird, E. A. et al. Effect of exchange interaction on spin dephasing in a double quantum dot. Phys. Rev. Lett. 97, 056801 (2006)
Petta, J. R. et al. Dynamic nuclear polarization with single electron spins. Phys. Rev. Lett. 100, 067601 (2008)
Press, D. et al. Ultrafast optical spin echo in a single quantum dot. Nature Photon. 4, 367–370 (2010)
Coish, W. A. & Loss, D. Singlet-triplet decoherence due to nuclear spins in a double quantum dot. Phys. Rev. B 72, 125337 (2005)
Assali, L. V. C. et al. Hyperfine interactions in silicon quantum dots. Phys. Rev. B 83, 165301 (2011)
DiVincenzo, D. P., Bacon, D., Kempe, J., Burkard, G. & Whaley, K. B. Universal quantum computation with the exchange interaction. Nature 408, 339–342 (2000)
Tomita, Y., Merrill, J. T. & Brown, K. R. Multi-qubit compensation sequences. N. J. Phys. 12, 015002 (2010)
West, J. R., Lidar, D. A., Fong, B. H. & Gyure, M. F. High fidelity quantum gates via dynamical decoupling. Phys. Rev. Lett. 105, 230503 (2010)
We thank C. M. Marcus for discussions, J. R. Petta for assistance with measurement techniques and B. H. Fong for assistance with hyperfine calculations. Sponsored by United States Department of Defense. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the United States Department of Defense or the US Government. Approved for public release, distribution unlimited.
The authors declare no competing financial interests.
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Maune, B., Borselli, M., Huang, B. et al. Coherent singlet-triplet oscillations in a silicon-based double quantum dot. Nature 481, 344–347 (2012). https://doi.org/10.1038/nature10707
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