Trapping and observing single atoms in the dark

An experimental sample trace of a trapping event is presented ⁸⁵Rb atoms have been launched from an atomic fountain along the y-direction. Arming the trigger at 210 ms after launch selects atoms with velocities <0.1 m/s. Because the probe field is resonant with the empty cavity, single atoms cause a steep decrease in the transmission (3). The storage times (A-B) are of the order of a few 10 ms. The Stark shift as measured by normal-mode spectroscopy is much smaller than the trap height. In conclusion, we have realized a blue-detuned intracavity dipole trap, now allowing measurements in cavity QED while preserving the free-space properties of the atom.