  Magic-Angle Twisted Bilayer Graphene shows a wide range of correlated phases
which are electrostatically tunable. Despite a growing knowledge of the
material, there is yet no consensus on the microscopic mechanisms driving its
superconducting phase. In particular, elucidating the symmetry and formation
mechanism of the superconducting phase may provide key insights for the
understanding of unconventional, strongly coupled and topological
superconductivity. A major obstacle to progress in this direction is that key
thermodynamic properties, such as specific heat, electron-phonon coupling and
superfluid stiffness, are extremely challenging to measure due to the 2D nature
of the material and its relatively low energy scales. Here, we use a
gate-defined, radio frequency-biased, Josephson junction to probe the
electronic dynamics of magic-angle twisted bilayer graphene (MATBG). We reveal
both the electronic quasiparticle dynamics, driven by their thermalization
through phonon scattering, as well as the condensate dynamics, driven by the
inertia of Cooper pairs. From these properties we recover the evolution of
thermalization rates, and the superfluid stiffness across the phase diagram.
Our findings favor an anisotropic or nodal pairing state and allow to estimate
the strength of electron-phonon coupling. These results contribute to
understanding the underlying mechanisms of superconductivity in MATBG while
establishing an easy-to-implement method for characterizing thermal and
superfluid properties of superconducting 2D materials.
