Title :
Design of the new NIM6 fountain with collecting atoms from a 3D MOT loading optical molasses
Author :
Fang Fang ; Weiliang Chen ; Kun Liu ; Nianfeng Liu ; Rui Suo ; Tianchu Li
Author_Institution :
Nat. Inst. of Metrol., Beijing, China
Abstract :
We report the design of a new cesium fountain clock NIM6, which is under construction in NIM. Besides some improvements on the vacuum system, Ramsey cavity and microwave synthesizer to reduce the Type B uncertainty. Another major improvement on NIM6 is to collect more atoms from a MOT loading optical molasses and optical pumping to get a better signal to noise ratio at the detection. The atom distribution will be more uniform compared with a 2D MOT loading optical molasses, and the diameter of the cloud can be adjusted by the intensity and detuning of lights during the post cooling to keep the collisional-induced frequency shift low. The atom numbers can be further increased by a new de-pumping - optical pumping procedure to pump atoms to the |F=3, mF=0> clock state directly. With a new cryogenic sapphire oscillator (CSO) based frequency synthesizer, NIM6 is aiming to reach the quantum projection noise, thus leading to a reduced Type A uncertainty compared with NIM5.
Keywords :
atomic clocks; cryogenic electronics; cryopumping; frequency synthesizers; laser cooling; optical pumping; oscillators; radiation pressure; 2D MOT loading optical molass; 3D MOT loading optical molass; CSO; NIM6 cesium fountain clock; Ramsey cavity; collisional-induced frequency shift low; cryogenic sapphire oscillator; frequency synthesizer; microwave synthesizer; optical pumping; post cooling; quantum projection noise; signal to noise ratio; type B uncertainty; vacuum system; Atom optics; Atomic clocks; Cavity resonators; Laser beams; Optical pumping; Atomic fountain clock; frequency measurement; optical pumping;
Conference_Titel :
Frequency Control Symposium & the European Frequency and Time Forum (FCS), 2015 Joint Conference of the IEEE International
Conference_Location :
Denver, CO
Print_ISBN :
978-1-4799-8865-5
DOI :
10.1109/FCS.2015.7138891