  A Berry phase can be added to the wavefunction of an isolated quantum dot by
adiabatically modulating a nonuniform electric field along a time-cycle. The
dot is tuned close to a three-level degeneracy, which provides a wide range of
possibilities of control. We propose to detect the accumulated phase by
capacitively coupling the dot to a double-path inteferometer. The effective
Hamiltonian for the phase-sensitive coupling is discussed in detail.
