Jiaqi Zhong

Test of Equivalence Principle at 10(-8) Level by a Dual-Species Double-Diffraction Raman Atom Interferometer.

We report an improved test of the weak equivalence principle by using a simultaneous 85Rb-87Rb dual-species atom interferometer. We propose and implement a four-wave double-diffraction Raman transition scheme for the interferometer, and demonstrate its ability in suppressing common-mode phase noise of Raman lasers after their frequencies and intensity ratios are optimized. The statistical uncertainty of the experimental data for Eötvös parameter η is 0.8×10(-8) at 3200 s. With various systematic errors corrected, the final value is η=(2.8±3.0)×10(-8). The major uncertainty is attributed to the Coriolis effect.

Extracting the differential phase in dual atom interferometers by modulating magnetic fields

We present a new scheme for measuring the differential phase in dual atom interferometers. The magnetic field is modulated in one interferometer, and the differential phase can be extracted without measuring the amplitude of the magnetic field by combining the ellipse and linear fitting methods. The gravity gradient measurements are discussed based on dual atom interferometers. Numerical simulation shows that the systematic error of the differential phase measurement is largely decreased when the duration of the magnetic field is symmetrically modulated. This combined fitting scheme has a high accuracy for measuring an arbitrary differential phase in dual atom interferometers

Note: A compact low-vibration high-performance optical shutter for precision measurement experiments

The optical shutter is an important component for atom-interferometry-based precision measurements. To decrease its vibration noise and improve its performance, we present a compact design with a direct current motor and a photodetector inserted in a compact aluminum structure. The photodetector in the blade is driven by the motor to move either in or out of the way of the laser beam. This design can suppress laser intensity fluctuation down to 0.26% over 6 h in the method of sample and hold proportional-integral-derivative feedback. It is also quiet via an electrical braking process which not only reduces its vibration noise by an order of magnitude but also quickens and stabilizes its switching performance. The shutter has a switching time of 0.8 ms and an activation delay of 8 ms with low jitters. Besides, the shutter can work for over ten million cycles normally and reliably.

Realization of a compact one-seed laser system for atom interferometer-based gravimeters

A simple and compact design of the laser system is important for realization of compact atom interferometers (AIs). We design and realize a simple fiber bench-based 780-nm laser system used for 85Rb AI-based gravimeters. The laser system contains only one 780 nm seed laser, and the traditional frequency-doubling-module is not used. The Raman beams are shared with one pair of the cooling beams by using a liquid crystal variable retarder based polarization control technique. This laser system is applied to a compact AI-based gravimeter, and a best gravity measurement sensitivity of 230 μGal/Hz1/2 is achieved. The gravity measurements for more than one day are also performed, and the long-term stability of the gravimeter is 5.5 μGal.

Normalized detection by using the blow-away signal in cold atom interferometry

We propose and realize a simple normalized detection scheme for cold atom interferometry. The detection of population in final atomic states is normalized to the blow-away fluorescence during initial state preparation. In this way, the detection system and procedure are both simplified. The reduced sensitivity to amplitude noise in atom interference signal is experimentally verified. Both amplitude noise in atom source and short term phase noise of interference fringes are suppressed by more than a factor of 10 with normalized detection.