High sensitive trap loss spectroscopic detection of the lowest vibrational levels of ultracold molecules

We present a controllable three-dimensional fluorescence modulation technique for the high sensitive trap loss detection of ultracold molecules. The lowest vibrational levels (v = 0 and 1) of the pure long-range state 0−g (6S1/2 + 6P3/2) of a cesium molecule are detected directly with high rotational resolution. Our technique proved to be a robust tool for effectively improving the detection sensitivity of trap loss spectroscopy.