  We report observations of the low-luminosity z = 5.50 quasar RD
J030117+002025 (RD0301 hereafter) at 250 GHz (1.20mm) using the Max-Planck
Millimeter Bolometer (MAMBO) array at the IRAM 30-meter telescope. The quasar
was detected with a 1.2mm flux density of 0.87 +-0.20 mJy. The lack of
detectable 1.4 GHz radio emission indicates that the millimeter emission is of
thermal nature, making RD0301 the most distant dust-emission source known. When
matching a 50K grey body thermal far-infrared (FIR) spectrum to the observed
millimeter flux we imply a FIR luminosity ~4x10^12 L_sun, which is comparable
to the quasar's optical luminosity. If the FIR luminosity arises from massive
star formation, the implied star formation rate would be ~600 M_sun/yr,
comparable to that of the starburst galaxies which dominate the average star
formation and FIR emission in the early Universe. The FIR luminosity of RD0301
is close to the average of that found in optically far more luminous
high-redshift quasars. The comparably high millimeter to optical brightness
ratio of RD0301 is further evidence for that there is no strong correlation
between the optical and millimeter brightness of high-redshift quasars,
supporting the idea that in high-redshift quasars the dust is not heated by the
AGN, but by starbursts.
