The progress of strontium optical clock at NIM

We report the experimental realization of
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Sr magneto-optical trap (MOT) operating at the wavelength of 461 nm and 689nm. The blue MOT is loaded via a 32 cm long spin-flip type Zeeman slower which enhances the MOT population by a factor of 44. We have trapped 1.6×10
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88Sr atoms with the use of 679nm and 707nm repumping laser. The
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Sr cloud has a temperature of about 2.3 mK, measured by recording the time evolution of the absorption signal. The 689nm laser used in our experiment has a line width of about 200Hz. To optimize the transfer efficiency, the laser spectrum is broadened by frequency modulation technique to about 2 MHz. The transfer efficiency from blue MOT to red MOT is about 20%.