Effect of Exchange Interaction on Spin Dephasing in a Double Quantum Dot

TL;DR

This paper investigates how exchange interaction influences spin dephasing in a double quantum dot, revealing saturation and damped oscillations when exchange and hyperfine energies are comparable, supported by quasistatic hyperfine field models.

Contribution

It provides experimental insights into the interplay between exchange interaction and hyperfine-induced dephasing in quantum dots, with quantitative comparison to theoretical models.

Findings

Dephasing saturates when exchange and hyperfine energies are comparable.

Damped oscillations of the spin correlator are observed under specific conditions.

Experimental results align with quasistatic hyperfine field predictions.

Abstract

We measure singlet-triplet dephasing in a two-electron double quantum dot in the presence of an exchange interaction which can be electrically tuned from much smaller to much larger than the hyperfine energy. Saturation of dephasing and damped oscillations of the spin correlator as a function of time are observed when the two interaction strengths are comparable. Both features of the data are compared with predictions from a quasistatic model of the hyperfine field.