No abstract

A cold rubidium atom fountain interferometry gravimeter with an active vibration isolator is demonstrated. The natural resonance frequency of the active vibration isolator is 0.016 Hz, and the vertical vibration noise is greatly reduced by a factor of 100 from 0.1 to 1 Hz. After substantial suppression of the vibration noise, the gravimeter reaches a sensitivity of 5.5 × 10 −8 g/Hz 1/2 . We measured the local gravitational acceleration g by this sensitive gravimeter with a resolution of 6.5 × 10 −9 g after 60 s and 1.5 × 10 −9 g after 2000 s integration time, which is comparable to the resolution of state-of-the-art atom gravimeters.

A layered structure of aluminum nitride (AlN)/silicon dioxide (SiO)/cubic silicon carbide with embedded electrodes, which enables the growth of high-quality AlN thin films, is proposed and studied. The phase velocity, coupling factor, and temperature coefficient of frequency (TCF) of surface acoustic waves in the proposed structure have been investigated using the finite-element method. The simulation results show that a high velocity of 5485 m/s and a large effective coupling factor ( K) of 1.45% can be simultaneously obtained for the first mode. The dramatic enhanced K of 10.5% is also obtainable on the proposed structure employing Sc0.4Al0.6N thin film. Besides, the excellent zero TCF is also achieved without deteriorating the coupling factor by adding an amorphous SiO overlay.

No abstract