Exploratory Chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30

We report exploratory \chandra\ observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by \chandra\ with a possible component of extended emission. The rest-frame 2-10 keV luminosity is 9.0${}_{-4.5}^{+9.1}$ $\times$ 10${}^{45}$ erg s${}^{-1}$ with inferred photon index of $\mathrm{\Gamma }$ = 3.03${}_{-0.70}^{+0.78}$. This quasar is X-ray bright, with inferred X-ray-to-optical flux ratio \aox
$=-1.22_{-0.05}^{+0.07}$, higher than the values found in other quasars of comparable ultraviolet luminosity. The properties inferred from this exploratory observation indicate that this ultraluminous quasar might be growing with super-Eddington accretion and probably viewed with small inclination angle. Deep X-ray observation will help to probe the plausible extended emission and better constraint the spectral features for this ultraluminous quasar.