Electron spin-flip correlations due to nuclear dynamics in driven GaAs double dots

Abstract

We present experimental data and associated theory for correlations in a series of experiments involving repeated Landau-Zener sweeps through the crossing point of a singlet state and a spin aligned triplet state in a GaAs double quantum dot containing two conduction electrons, which are loaded in the singlet state before each sweep, and the final spin is recorded after each sweep. The experiments reported here measure correlations on time scales from 4 $\mu$s to 2 ms. When the magnetic field is aligned in a direction such that spin-orbit coupling cannot cause spin flips, the correlation spectrum has prominent peaks centered at zero frequency and at the differences of the Larmor frequencies of the nuclei, on top of a frequency-independent background. When the spin-orbit field is relevant, there are additional peaks, centered at the frequencies of the individual species. A theoretical model which neglects the effects of high-frequency charge noise correctly predicts the positions of the observed peaks, and gives a reasonably accurate prediction of the size of the frequency-independent background, but gives peak areas that are larger than the observed areas by a factor of two or more. The observed peak widths are roughly consistent with predictions based on nuclear dephasing times of the order of 60 $\mu$s. However, there is extra weight at the lowest observed frequencies, which suggests the existence of residual correlations on the scale of 2 ms. We speculate on the source of these discrepancies.

20 pages, 5 figures, 2 tables

References in corpus (16)

• Coherent control of a single electron spin with electric fields
• Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits
• Prospects for Spin-Based Quantum Computing
• Universal quantum control of two-electron spin quantum bits using dynamic nuclear polarization
• Electrometry Using Coherent Exchange Oscillations in a Singlet-Triplet-Qubit
• Theory of electron spin decoherence by interacting nuclear spins in a quantum dot
• Direct Measurement of the Spin-Orbit Interaction in a Two-Electron InAs Nanowire Quantum Dot
• Enhancing the Coherence of a Spin Qubit by Operating it as a Feedback Loop That Controls its Nuclear Spin Bath
• Suppressing qubit dephasing using real-time Hamiltonian estimation
• Electron Spin Dephasing due to Hyperfine Interactions with a Nuclear Spin Bath
• Hyperfine-mediated gate-driven electron spin resonance
• Dynamic Nuclear Polarization with Single Electron Spins
• Measurement of Temporal Correlations of the Overhauser Field in a Double Quantum Dot
• Semiclassical dynamics and long time asymptotics of the central-spin problem in a quantum dot
• Phase Transitions in Dissipative Quantum Transport and Mesoscopic Nuclear Spin Pumping
• High-field optically detected nuclear magnetic resonance in GaAs