Recent Progress of Time and Frequency Research in NIM

摘要

The recent evaluation of the second cesium fountain NIM5 at National Institute of Metrology(NIM) shows a total relative uncertainty of 2×10~(-15). The strontium optical clock project has successfully transferred atoms from broad line cooling to narrow line cooling. About 10~7 ~(88)Sr atoms have been cooled down to 2uK, ready to be loaded into 1 dimensional (1D) optical lattice. The clock transition interrogation laser is locked to a horizontally oriented high finesse cavity. The linewidth of this laser is reduced to 100Hz level. A fiber based optical frequency comb is being built, which can be used to synthesize ultra-stable microwave frequency for the fountains in the future.