Dephasing of electrons by two-level defects in quantum dots - art. no. 195301

The electron dephasing time tau (phi) in a diffusive quantum dot is calcula ted by considering the interaction between the electron and dynamical defec ts, modeled as two level systems. Using the standard tunneling model of gla sses, we obtain a linear temperature dependence of 1/tau (phi), consistent with the experimental observation. However, we find that. in order to obtai n dephasing times on the order of nanoseconds, the number of two-level defe cts needs to be substantially larger than the typical concentration in glas ses. We also find a finite system-size dependence of tau (phi), which can b e used to probe the effectiveness of surface-aggregated defects.