  Quantum dots are considered building blocks for future quantum information
circuits. We present here experimental results on a quantum dot circuit
consisting of three quantum dots with controlled electron numbers down to one
per dot and tunable coupling. We experimentally map out for the first time the
stability diagram of the triatomic system and reveal the existence of quadruple
points, a signature of the three dots being in resonance. In their vicinity we
observe a surprising effect, a 'cloning' of charge transfer transitions related
to charge and spin reconfigurations. The experimental results are reproduced by
equivalent circuit analysis and Hubbard models.
