Evolution of Coulomb blockade spectra in parallel coupled quantum dots

We report low-temperature conductance measurements in the Coulomb blockade regime on two nominally identical tunnel-coupled quantum dots in parallel d efined electrostatically in the two-dimensional gas of a GaAs/AlGaAs hetero structure. We find that the Coulomb blockade spectra of such devices exhibi t two distinct sets of peaks, each of which behaves differently with varyin g interdot tunnel conductance and with temperature. The results conform to recent theories regarding the role of interdot quantum charge fluctuations, and provide evidence for the possible role of inelastic cotunneling betwee n dots at finite interdot conductances. (C) 1999 American Institute of Phys ics. [S0003-6951(99)03929-7].