Phonon-Mediated Electron-Spin Phase Diffusion in a Quantum Dot

An effective spin relaxation mechanism that leads to electron spin decoherence in a quantum dot is proposed. In contrast with the common calculations of spin-flip transitions between the Kramers doublets, we take into account a process of phonon-mediated fluctuation in the electron spin precession and subsequent spin phase diffusion. Specifically, we consider modulations in the longitudinal $g$ factor and hyperfine interaction induced by the phonon-assisted transitions between the lowest electronic states. Prominent differences in the temperature and magnetic field dependence between the proposed mechanism and the spin-flip transitions are expected to facilitate its experimental verification. Numerical estimation demonstrates highly efficient spin relaxation in typical semiconductor quantum dots.

Figure 1

Decoherence factor $F({\delta }_0/2T)$ [Eq. (11)] as a function of temperature.