Detection of macroscopic quantum coherence of a Bose-Einstein condensate by electronic spin echo

this paper the conventional electronic spin echo technique is proposed to detect the macroscopic quantum coherence of a Bose-Einstein condensate. In this technique, a pi/2 microwave pulse followed by a pi pulse with an appropriate delay is used to excite the Zeeman levels of a Bose condensed gas. After the two pulses, a spin echo pulse is generated due to the dephasing and rephasing processes in the gas. We show that the properties of the spin echo signal depends on the temperature of the gas. If a condensate exists in the gas, the echo signal can reflect the macroscopic quantum coherence of the Bose-Einstein condensate. The detection technique doesn't destroy the sample.