Andersen M F, Kaplan A, Davidson N
Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel.
Phys Rev Lett. 2003 Jan 17;90(2):023001. doi: 10.1103/PhysRevLett.90.023001. Epub 2003 Jan 13.
We investigate the dephasing of ultra cold 85Rb atoms trapped in an optical dipole trap and prepared in a coherent superposition of their two hyperfine ground states by interaction with a microwave pulse. We demonstrate that the dephasing, measured as the Ramsey fringe contrast, can be reversed by stimulating a coherence echo with a pi pulse between the two pi / 2 pulses, in analogy to the photon echo. We also demonstrate that "echo spectroscopy" can be used to study the quantum dynamics in the trap even when more than 10(6) states are thermally populated and to study the crossover from quantum to classical dynamics.
