Abstract
We study electron spin decoherence in a two-electron double quantum dot due to the hyperfine interaction, under spin-echo conditions as studied in recent experiments. We develop a semi-classical model for the interaction between the electron and nuclear spins, in which the time-dependent Overhauser fields induced by the nuclear spins are treated as classical vector variables. Comparison of the model with experimentally-obtained echo signals allows us to quantify the contributions of various processes such as coherent Larmor precession and spin diffusion to the nuclear spin evolution.
Highlights
In recent years, electron spin qubits in solid-state quantum dots have emerged as promising candidates for the implementation of quantum information processing1–8
The aim of this paper is to demonstrate that a wide array of complex dynamical phenomena in two-electron spin echo measurements, such as those of Ref. 18, can be understood within the context of a semi-classical treatment of the nuclear spin bath
With the above-described picture in mind, below we focus on the Hahn echo experiment in GaAs double quantum dots, where each electron spin interacts weakly with N ≈ 106 nuclear spins
Summary
Electron spin qubits in solid-state quantum dots have emerged as promising candidates for the implementation of quantum information processing. The aim of this paper is to demonstrate that a wide array of complex dynamical phenomena in two-electron spin echo measurements, such as those of Ref. 18, can be understood within the context of a semi-classical treatment of the nuclear spin bath. We provide a systematic discussion of this semi-classical treatment, which relies on a low-order expansion of the qubit evolution in the inverse of the number of nuclear spins and in the hyperfine coupling. Using this approach, we identify the relevant physical processes which govern nuclear spin evolution and electron spin coherence, as measured by the spin-echo signal.
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