Atom Femto Trap
Basic idea of localization of the atom by a periodic sequence of femtosecond laser pulses is as follows. Laser light pulses are perpendicularly reflected from a mirror. The incident and reflected pulses "collide" at a certain distance from the mirror. The energy of a single femtosecond pulse is spatially localized at a distance l = c/tp , where c is the speed of light and tp is the pulse duration. When the laser pulse is extremely short, i.e., equal to the period of light, its spatial size is equal to the laser wavelength: l =λ. The region where pulses collide is the localization region for the atom and has the same size. Depending on the phase relations between the incident and reflected pulses, either a maximum or minimum of the laser-field intensity arises at the center of the overlapping pulses due to their interference. The atom that is placed in the pulse region is subjected to the gradient force that is directed toward the center of the pulse overlapping region when the laser frequency is lower than the atomic transition frequency and intensity is maximal. It has been shown that the atom can be localized with absolute accuracy in the nanometer range. The time interval during which the atom is situated in the laser field is only 10 -7–10 -8 of the total localization time interval.
The lifetime of the atom in the optical dipole traps is limited by (1) the velocity diffusion of the atom due to spontaneously emitted photons of the localizing laser field and (2) the inevitable presence of chaos in the dynamics of the system subjected to periodic short kicks. It has been shown that the atom can be localized with absolute accuracy in the nanometer range. The time interval during which the atom is situated in the laser field is only 10 -7–10 -8 of the total localization time interval [1].
