  We present dynamical and structural scaling relations of quiescent galaxies
at z=2, including the dynamical mass-size relation and the first constraints on
the fundamental plane (FP). The backbone of the analysis is a new, very deep
VLT/X-shooter spectrum of a massive, compact, quiescent galaxy at z=2.0389. We
detect the continuum between 3700-22000A and several strong absorption features
(Balmer series, Ca H+K, G-band), from which we derive a stellar velocity
dispersion of 318 +/- 53 km/s. We perform detailed modeling of the continuum
emission and line indices and derive strong simultaneous constraints on the
age, metallicity, and stellar mass. The galaxy is a dusty (A_V=0.77
(+0.36,-0.32)) solar metallicity (log(Z/Zsun) = 0.02 (+0.20,-0.41)) post
starburst galaxy, with a mean luminosity weighted log(age/yr) of 8.9 +/- 0.1.
The galaxy formed the majority of its stars at z>3 and currently has little or
no ongoing star formation. We compile a sample of three other z~2 quiescent
galaxies with measured velocity dispersions, two of which are also post
starburst like. Their dynamical mass-size relation is offset significantly less
than the stellar mass-size relation from the local early type relations, which
we attribute to a lower central dark matter fraction. Recent cosmological
merger simulations qualitatively agree with the data, but can not fully account
for the evolution in the dark matter fraction. The z~2 FP requires additional
evolution beyond passive stellar aging, to be in agreement with the local FP.
The structural evolution predicted by the cosmological simulations is
insufficient, suggesting that additional, possibly non-homologous structural
evolution is needed.
