Fold optics path: an improvement for an atomic fountain

A fold optical path is utilized to capture and launch atoms in the atomic fountain.This improved technique reduces the laser power needed by 60 percent,facilitates suppression of the laser power fluctuations,and leads to a more simple and stable system.     

Progress of the 87Rb Fountain Clock

A fountain atomic clock based on cold 87Rb atoms has been in operation in our laboratory for several months. We therefore report the design of the rubidium fountain clock including its physical package, optical system and daily operation. Ramsey fringes have been attained with the signal to noise ratio of about 100.     

Proposal of a dual-ball atomic fountain clock

A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time,which works like"two fountains",but is more compact since most components of the"two fountains" are shared.It is expected to improve the stability of the fountain markedly.     

Magnetic field measurement on ~(87)Rb atomic fountain clock

<正>An experiment on measuring the magnetic field in Ramsey interaction region of the atomic fountain clock by detecting the Zeeman frequency shift of ~(87)Rb hyperfine transition is presented.By mu-metal shielding and coils compensating,the magnetic fluctuations resulting from asymmetry and instability are less than 10 and 0.025 nT,respectively.The relative frequency uncertainty of atomic fountain clock caused by the magnetic field is less than 5.4×10~(-16).     

Observation of Modulation Transfer Spectroscopy in the Deep Modulation Regime

We observe the modulation transfer spectroscopy on the D2 line of ^87Rb in a rubidium cell with acoustic-optic modulator in the deep modulation regime. In this regime, the sidebands of the pump beam are involved in the four-wave mixing processes, which increase the signal gradients and the peak-to-peak amplitudes of both the absorption and dispersion components.     

Realization of an 85Rb Atomic Fountain

An atomic fountain with ^85 Rb cold atoms is reported. A series of time-of-flight signals is obtained, and the measured temperature of the cold atomic cloud is about 2.4μK. It will have potential new applications in the precise measurement of fundamental constants and the proof of the Einstein＇s equivalence principle.     

Magnetic field measurement based on a stimulated two-photon Raman transition

The magnetic field in the microwave interaction zone of the fountain atomic clock was measured by stimulated Raman transitions.By measuring the two-photon transition frequency between the Zeeman levels of the two ground states,we achieved a magnetic field measurement accuracy of the order of 0.28 nT.This method is immune to the Doppler shift and the AC Stark shift.The second order Zeeman shift of the fountain clock is 170.7×10-15,with the uncertainty of 7.2×10-16.