  We have developed an etching process to fabricate a quantum dot and a nearby
single electron transistor as a charge detector in a single layer graphene. The
high charge sensitivity of the detector is used to probe Coulomb diamonds as
well as excited spectrum in the dot, even in the regime where the current
through the quantum dot is too small to be measured by conventional transport
means. The graphene based quantum dot and integrated charge sensor serve as an
essential building block to form a solid-state qubit in a nuclear-spin-free
quantum world.
