Using the IRAM interferometer we have detected J=4 \rightarrow 3 and 5 \rightarrow 4 CO line emission toward the radio quiet quasar PSS 2322+1944 .
At a redshift of z _ { CO } = 4.1199 this is the fourth and strongest detection of CO at z > 4 .
The velocity-integrated CO J=4 \rightarrow 3 and J=5 \rightarrow 4 line fluxes are 4.21 \pm 0.40 and 3.74 \pm 0.56 \thinspace Jy \thinspace km \thinspace s ^ { -1 } , and the linewidth is \approx 300 \thinspace kms ^ { -1 } .
The CO J=10 \rightarrow 9 was searched for but not detected with an upper intensity limit of 30 mJy .
The 1.35 mm ( 250 \mu m rest wavelength ) continuum flux density is 7.5 \pm 1.3 mJy , in agreement with previous bolometer measurements at 1.2 mm with the 30-m IRAM telescope .
The 3 mm ( 580 \mu m rest wavelength ) continuum is not detected with a 3 \sigma upper limit of 0.7 mJy .
We also report observations of the 450 \mu m continuum in PSS 2322+1944 using the SCUBA array at the JCMT .
The quasar was detected with a 450 \mu m flux density of 79 \pm 19 \thinspace mJy .
At the angular resolution of 4 \aas@@fstack { \prime \prime } 8 \times 2 \aas@@fstack { \prime \prime } 1 at 1.3 mm and 6 \aas@@fstack { \prime \prime } 2 \times 4 \aas@@fstack { \prime \prime } 9 at 3.2 mm , the interferometer observations do not show evidence of spatial extension in the continuum or CO line emission .
Assuming no gravitational magnification , we estimate a molecular gas mass of \approx 2.5 \times 10 ^ { 11 } \thinspace M _ { \odot } .
The molecular gas is warm ( 40 - 100 \thinspace K ) and dense ( 10 ^ { 3.5 } -10 ^ { 4.1 } \thinspace cm ^ { -3 } ) .
The infrared-to-CO luminosity ratio is \approx 185 \thinspace L _ { \odot } \thinspace ( K \thinspace km \thinspace s ^ { -1 } % \thinspace pc ^ { 2 } ) ^ { -1 } , comparable to the values found for ultraluminous infrared galaxies .
The detection of CO emission in this high redshift QSO provides further evidence that the radio emission and the millimeter to submillimeter continuum emission are predominantly powered by a starburst which is coeval with the AGN activity .