Coulomb Blockade Oscillations in the Thermopower of Open Quantum Dots

We consider Coulomb blockade oscillations of thermoelectric coefficients of a single electron transistor based on a quantum dot strongly coupled to one of the leads. An analytic expression for the thermopower as a function of temperature $T$ and the reflection amplitude $r$ in the quantum point contact is obtained. Two regimes can be identified: $T\ll E_C|r{|}^2$ and $T\gg E_C|r{|}^2$, where $E_C$ is the charging energy of the dot. The former regime is characterized by a weak logarithmic dependence of the thermopower on the reflection coefficient, in the latter the thermopower is linear in the reflection coefficient $|r{|}^2$ but depends on temperature only logarithmically.