Absolute frequency measurement of a 176 Lu+,(cubed D 1) standard against the NRC-FCs2 fountain with 2.6 times10-16 uncertainty
Researchers measured an improved absolute frequency of a 176Lu+ optical standard against a Canadian caesium fountain clock using a GPS link. The result achieved a fractional uncertainty of 2.6 x 10^-16, significantly reducing previous errors and meeting stringent international standards for atomic clocks.