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.

Locking laser frequency of up to 40 GHz offset to a reference with a 10 GHz electro-optic modulator.

We demonstrate a method to lock a laser frequency of up to 40 GHz offset to a reference using a 10 GHz waveguide-type electro-optic modulator (EOM). Offsetting is provided by the EOM sidebands, and first- to fourth-order sidebands are generated by changing the power of the EOM's driving radio frequency. By scanning the driving frequency across the 10 GHz bandwidth, the output laser frequency can be set at any point in an 80 GHz range (from -40 to 40 GHz) by locking a sideband to the reference.