High Accuracy Correction of Blackbody Radiation Shift in an Optical Lattice Clock

We have determined the frequency shift that blackbody radiation is inducing on the 5s(2) S-1(0)-5s5p P-3(0) clock transition in strontium. Previously its uncertainty limited the uncertainty of strontium lattice clocks to 1 x 10(-16). Now the uncertainty associated with the blackbody radiation shift correction translates to a 5 x 10(-18) relative frequency uncertainty at room temperature. Our evaluation is based on a measurement of the differential dc polarizability of the two clock states and on a modeling of the dynamic contribution using this value and experimental data for other atomic properties. DOI: 10.1103/PhysRevLett.109.263004