### Abstract

Silicon quantum dots are considered an excellent platform for spin qubits, partly due to their weak spin-orbit interaction. However, the sharp interfaces in the heterostructures induce a small but significant spin-orbit interaction that degrades the performance of the qubits or, when understood and controlled, could be used as a powerful resource. To understand how to control this interaction, we build a detailed profile of the spin-orbit interaction of a silicon metal-oxide-semiconductor double quantum-dot system. We probe the derivative of the Stark shift, g-factor and g-factor difference for two single-electron quantum-dot qubits as a function of external magnetic field and find that they are dominated by spin-orbit interactions originating from the vector potential, consistent with recent theoretical predictions. Conversely, by populating the double dot with two electrons, we probe the mixing of singlet and spin-polarized triplet states during electron tunneling, which we conclude is dominated by momentum-term spin-orbit interactions that vary from 1.85 MHz up to 27.5 MHz depending on the magnetic field orientation. Finally, we exploit the tunability of the derivative of the Stark shift of one of the dots to reduce its sensitivity to electric noise and observe an 80% increase in T2∗. We conclude that the tuning of the spin-orbit interaction will be crucial for scalable quantum computing in silicon and that the optimal setting will depend on the exact mode of qubit operations used.

Original language | English |
---|---|

Article number | 021028 |

Journal | Physical Review X |

Volume | 9 |

Issue number | 2 |

DOIs | |

Publication status | Published - 2019 May 10 |

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### ASJC Scopus subject areas

- Physics and Astronomy(all)

### Cite this

*Physical Review X*,

*9*(2), [021028]. https://doi.org/10.1103/PhysRevX.9.021028

**Controlling Spin-Orbit Interactions in Silicon Quantum Dots Using Magnetic Field Direction.** / Tanttu, Tuomo; Hensen, Bas; Chan, Kok Wai; Yang, Chih Hwan; Huang, Wister Wei; Fogarty, Michael; Hudson, Fay; Itoh, Kohei M; Culcer, Dimitrie; Laucht, Arne; Morello, Andrea; Dzurak, Andrew.

Research output: Contribution to journal › Article

*Physical Review X*, vol. 9, no. 2, 021028. https://doi.org/10.1103/PhysRevX.9.021028

}

TY - JOUR

T1 - Controlling Spin-Orbit Interactions in Silicon Quantum Dots Using Magnetic Field Direction

AU - Tanttu, Tuomo

AU - Hensen, Bas

AU - Chan, Kok Wai

AU - Yang, Chih Hwan

AU - Huang, Wister Wei

AU - Fogarty, Michael

AU - Hudson, Fay

AU - Itoh, Kohei M

AU - Culcer, Dimitrie

AU - Laucht, Arne

AU - Morello, Andrea

AU - Dzurak, Andrew

PY - 2019/5/10

Y1 - 2019/5/10

N2 - Silicon quantum dots are considered an excellent platform for spin qubits, partly due to their weak spin-orbit interaction. However, the sharp interfaces in the heterostructures induce a small but significant spin-orbit interaction that degrades the performance of the qubits or, when understood and controlled, could be used as a powerful resource. To understand how to control this interaction, we build a detailed profile of the spin-orbit interaction of a silicon metal-oxide-semiconductor double quantum-dot system. We probe the derivative of the Stark shift, g-factor and g-factor difference for two single-electron quantum-dot qubits as a function of external magnetic field and find that they are dominated by spin-orbit interactions originating from the vector potential, consistent with recent theoretical predictions. Conversely, by populating the double dot with two electrons, we probe the mixing of singlet and spin-polarized triplet states during electron tunneling, which we conclude is dominated by momentum-term spin-orbit interactions that vary from 1.85 MHz up to 27.5 MHz depending on the magnetic field orientation. Finally, we exploit the tunability of the derivative of the Stark shift of one of the dots to reduce its sensitivity to electric noise and observe an 80% increase in T2∗. We conclude that the tuning of the spin-orbit interaction will be crucial for scalable quantum computing in silicon and that the optimal setting will depend on the exact mode of qubit operations used.

AB - Silicon quantum dots are considered an excellent platform for spin qubits, partly due to their weak spin-orbit interaction. However, the sharp interfaces in the heterostructures induce a small but significant spin-orbit interaction that degrades the performance of the qubits or, when understood and controlled, could be used as a powerful resource. To understand how to control this interaction, we build a detailed profile of the spin-orbit interaction of a silicon metal-oxide-semiconductor double quantum-dot system. We probe the derivative of the Stark shift, g-factor and g-factor difference for two single-electron quantum-dot qubits as a function of external magnetic field and find that they are dominated by spin-orbit interactions originating from the vector potential, consistent with recent theoretical predictions. Conversely, by populating the double dot with two electrons, we probe the mixing of singlet and spin-polarized triplet states during electron tunneling, which we conclude is dominated by momentum-term spin-orbit interactions that vary from 1.85 MHz up to 27.5 MHz depending on the magnetic field orientation. Finally, we exploit the tunability of the derivative of the Stark shift of one of the dots to reduce its sensitivity to electric noise and observe an 80% increase in T2∗. We conclude that the tuning of the spin-orbit interaction will be crucial for scalable quantum computing in silicon and that the optimal setting will depend on the exact mode of qubit operations used.

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U2 - 10.1103/PhysRevX.9.021028

DO - 10.1103/PhysRevX.9.021028

M3 - Article

AN - SCOPUS:85070066570

VL - 9

JO - Physical Review X

JF - Physical Review X

SN - 2160-3308

IS - 2

M1 - 021028

ER -