Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins

Abstract

We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96%, a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots.

Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance

“…Therefore, transverse nuclear fluctuations provide an additional dephasing mechanism which becomes progressively more important, until the maximum effect is reached at δR/δx 1.8. We will discuss how the effect of δh xy becomes dominant over δh z in a regime of sufficiently strong EDSR drive, which was already realized by recent experiments [10].…”

“…Thus, Eq. (13) shows that it is always advantageous to apply a stronger drive and the effect of the hyperfine interaction on π-rotation error can be reduced below any desired threshold with a sufficiently large δR/δx [10].…”

“…Thus, electric dipole spin resonance (EDSR) was developed relying on either spin-orbit couplings [5,6] or the inhomogeneous magnetic field induced by a micromagnet [7,8]. The effectiveness of EDSR is highlighted by recent experiments, which could demonstrate Rabi oscillations with frequencies larger than 100 MHz for both approaches [9,10]. To further improve the performance of such spin manipulation schemes, it is important to characterize relevant dephasing mechanisms, and especially those which might become dominant at strong electric drive.…”

“…The resulting power-law decay and a universal π/4 phase shift of the Rabi oscillations were accurately verified [11], confirming the predominance of nuclear spins over other sources of dephasing. While EDSR experiments were also generally interpreted assuming a power-law decay, the expected t −1/2 dependence is violated at the larger values of the drive [9,10,12]. Especially, Ref.…”

“…Especially, Ref. [10] has demonstrated striking deviations from the ESR behavior, including a crossover from power-law to gaussian decay. It is also known that the electron motion, as well as the presence of the drive, can have substantial effects on spin dynamics and decoherence [13][14][15][16][17].…”