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Spin-orbit signatures in the dynamics of singlet-triplet qubits in double quantum dots

E. Cota, Sergio E. Ulloa, Juan E. Rolon

Apr 21, 20200 citations

Analyzing the fidelity of a singlet-triplet spin-orbit qubit in silicon using gate set tomography

Chloé Bureau-Oxton, Kenneth Rudinger, N. Tobias Jacobson +9 more

Bulletin of the American Physical SocietyMar 5, 20190 citations

Implications of the Spin-Orbit Effect for Singlet-Triplet Qubit Operation.

Malcolm S. Carroll

µmSpin-orbit effects in silicon have long been considered of minor importance for the operation of spin qubits.Contrary to this belief, recent and growing amounts of evidence in systems like spin 1/2 and atomic-precision devices seem to indicate otherwise, but the exact mechanisms and implications are not well understood.In this work, we use a metal-oxide-semiconductor and poly-Si (metal-free) double quantum dot singlet-triplet qubit as a sensitive probe of the spin-orbit effect.We first show that a strong magnetic field enables rotations between the singlet S and unpolarized triplet T 0 , an effect which amounts to an effective g-factor difference between the two quantum dots and is affected by gate voltages.Twoaxis control and single shot readout of the qubit is used to study AC resonant control in the deep detuning regime and achieve few microsecond Rabi flip times.Perhaps surprisingly, singlet-triplet qubits "just turn" without engineering feats.Secondly, we investigate a different effect of the spin-orbit interaction on the S-T -transition and its impact on schemes like dynamic nuclear polarization.Our results shed light on the implications of spin-orbit interaction for the operation of spin qubits in silicon.µmSpin-orbit effects in silicon have long been considered of minor importance for the operation of spin qubits.Contrary to this belief, recent and growing amounts of evidence in systems like spin 1/2 and atomic-precision devices seem to indicate otherwise, but the exact mechanisms and implications are not well understood.In this work, we use a metal-oxide-semiconductor and poly-Si (metal-free) double quantum dot singlet-triplet qubit as a sensitive probe of the spin-orbit effect.We first show that a strong magnetic field enables rotations between the singlet S and unpolarized triplet T 0 , an effect which amounts to an effective g-factor difference between the two quantum dots and is affected by gate voltages.Twoaxis control and single shot readout of the qubit is used to study AC resonant control in the deep detuning regime and achieve few microsecond Rabi flip times.Perhaps surprisingly, singlet-triplet qubits "just turn" without engineering feats.Secondly, we investigate a different effect of the spin-orbit interaction on the S-T -transition and its impact on schemes like dynamic nuclear polarization.Our results shed light on the implications of spin-orbit interaction for the operation of spin qubits in silicon.

Mar 11, 20190 citations

Controlling a Singlet-Triplet Spin Qubit

J. R. Petta

Bulletin of the American Physical SocietyMar 17, 20060 citations

Spin-orbit signatures in the dynamics of singlet-triplet qubits in double quantum dots

Juan E. Rolon, E. Cota, Sergio E. Ulloa

We characterize numerically and analytically the signatures of the spin-orbit interaction in a two-electron GaAs double quantum dot in the presence of an external magnetic field. In particular, we obtain the return probability of the singlet state by simulating Landau-Zener voltage detuning sweeps which traverse the singlet-triplet ($S\ensuremath{-}{T}_{+}$) resonance. Our results indicate that non-spin-conserving interdot tunneling processes arising from the spin-orbit interaction have well defined signatures. These allow direct access to the spin-orbit interaction scales and are characterized by a frequency shift and Fourier amplitude modulation of the Rabi flopping dynamics of the singlet-triplet qubits $S\ensuremath{-}{T}_{0}$ and $S\ensuremath{-}{T}_{+}$. By applying the Bloch-Feshbach projection formalism, we demonstrate analytically that the aforementioned effects originate from the interplay between spin-orbit interaction and processes driven by the hyperfine interaction between the electron spins and those of the GaAs nuclei.We characterize numerically and analytically the signatures of the spin-orbit interaction in a two-electron GaAs double quantum dot in the presence of an external magnetic field. In particular, we obtain the return probability of the singlet state by simulating Landau-Zener voltage detuning sweeps which traverse the singlet-triplet ($S\ensuremath{-}{T}_{+}$) resonance. Our results indicate that non-spin-conserving interdot tunneling processes arising from the spin-orbit interaction have well defined signatures. These allow direct access to the spin-orbit interaction scales and are characterized by a frequency shift and Fourier amplitude modulation of the Rabi flopping dynamics of the singlet-triplet qubits $S\ensuremath{-}{T}_{0}$ and $S\ensuremath{-}{T}_{+}$. By applying the Bloch-Feshbach projection formalism, we demonstrate analytically that the aforementioned effects originate from the interplay between spin-orbit interaction and processes driven by the hyperfine interaction between the electron spins and those of the GaAs nuclei.

arXiv:1607.07852Physical review. B./Physical review. BMay 8, 20174 citations

Entanglement of Singlet-Triplet Qubits

Michael Shulman

Bulletin of the American Physical SocietyMar 18, 20130 citations

Implications of the Spin-Orbit Effect for Singlet-Triplet Qubit Operation

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