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$^{+9.1}_{-4.5}$ $\times$ 10$^{45}$ erg s$^{-1}$ with inferred photon index of $\Gamma$ = 3.03$^{+0.78}_{-0.70}$. This quasar is X-ray bright, with inferred X-ray-to-optical flux ratio \aox\ $=-1.22^{+0.07}_{-0.05}$, 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.