  We report tunneling spectroscopy experiments on a bilayer graphene double
quantum dot device that can be tuned by all-graphene lateral gates. The
diameter of the two quantum dots are around 50 nm and the constrictions acting
as tunneling barriers are 30 nm in width. The double quantum dot features
addition energies on the order of 20 meV. Charge stability diagrams allow us to
study the tunable interdot coupling energy as well as the spectrum of the
electronic excited states on a number of individual triple points over a large
energy range. The obtained constant level spacing of 1.75 meV over a wide
energy range is in good agreement with the expected single-particle energy
spacing in bilayer graphene quantum dots. Finally, we investigate the evolution
of the electronic excited states in a parallel magnetic field.
