  The discovery of giant quasar Ly$\alpha$ nebulae at $z>2$ has opened up the
possibility to directly study in emission the Circumgalactic and Intergalactic
Medium (CGM/IGM). However, the resonant nature of the Ly$\alpha$ line and its
different emission mechanisms hamper the ability to constrain both the
kinematics and physical properties of the CGM/IGM. Here, we present results of
a pilot project aiming at the detection of CGM H$\alpha$ emission, a line which
does not suffer from these limitations. To this end, we first used KCWI to
detect Ly$\alpha$ emission around three bright quasars with $2.25<z<2.27$, a
range which is free from bright IR sky lines for H$\alpha$, and then selected
the most extended nebula for H$\alpha$ follow-up with MOSFIRE. Within the
MOSFIRE slit, we detected H$\alpha$ emission extending up to 20 physical kpc
with a total H$\alpha$ flux of F$_{ \textrm{H}\alpha}$=(9.5 $\pm$ 0.9) $\times$
10$^{-18}$ erg s$^{-1}$ cm$^{-2}$. Considering the Ly$\alpha$ flux in the same
region, we found F$_{ \textrm{Ly}\alpha}$/F$_{ \textrm{H}\alpha}$=3.7 $\pm$ 0.3
consistent with that obtained for the Slug Nebula at z$=2.275$ and with
recombination radiation. This implies high densities or a very broad density
distribution within the CGM of high-redshift quasars. Moreover, the H$\alpha$
line profile suggests the presence of multiple emitting components overlapping
along our line-of-sight and relatively quiescent kinematics, which seems
incompatible with either quasar outflows capable of escaping the potential well
of the host halo or disk-like rotation in a massive halo
($>10^{12}$M$_{\odot}$).
