Saturation of Phase Breaking in an Open Ballistic Quantum Dot

A variation in the saturated phase-breaking time in a ballistic quantum dot is found to occur as the size is varied. This variation differs from that observed earlier, in which a transition from quasi-two-dimensional to zero-dimensional behavior was thought to occur. Instead, these results suggest that the saturated phase-breaking rate is governed by a change in the total number of electrons within the dot. At higher temperatures, the phase breaking is governed by coupling to the quantum wire leads, and ${\tau }_{\phi }$ may show the $T^{-2/3\mathrm{}}$ variation expected for a one-dimensional wire due to the electron-electron interaction.