Atomic Micromotion and Geometric Forces in a Triaxial Magnetic Trap

Abstract

Nonadiabatic motion of Bose-Einstein condensates of rubidium atoms arising from the dynamical nature of a time-orbiting-potential (TOP) trap was observed experimentally. The orbital micromotion of the condensate in velocity space at the frequency of the rotating bias field of the TOP was detected by a time-of-flight method. A dependence of the equilibrium position of the atoms on the sense of rotation of the bias field was observed. We have compared our experimental findings with numerical simulations. The nonadiabatic following of the atomic spin in the trap rotating magnetic field produces geometric forces acting on the trapped atoms.

Spin gauge fields: From Berry phase to topological spin transport and Hall effects

“…Similar equations have been derived in [55] in the course of the Lagrange description of the wave packet dynamics. Particular cases of these are discussed in many papers on the topological spin transport [21][22][23][24][25][26][54][55][56][57][58][59]63,65,68,76,84,[86][87][88][89][90][91]. The first terms in the right-hand sides of Eqs.…”

“…Indeed, just after the discovery of the Berry phase the manifestations of the socalled geometric force were revealed [17][18][19][20][21][22][23][24][25][26]. And almost simultaneously with the discovering of the Berry phase, Thouless proposed a mechanism of adiabatic transport of particles [26].…”

“…Clearly the basic variations in the particleÕs transport are associated with the forces responsible for the shift of the particle across the principal motion (the longitudinal shifts are small, being of order of e in the adiabatic approximation, and are not detectable on the background of the basic transport). Among them are primarily the spin analogues of the Lorentz force in the p-and r-spaces (see [17][18][19][20][21][22][23][24][25][26]39,47,[54][55][56][57][58][59][60][61][62][63]65,68,76,84,[86][87][88][89][90][91]). This is the reason why the topological spin transport of free particles is frequently associated with the analogues of the magnetic field and the Hall effects.…”

Manipulation of a Bose-Einstein condensate by a time-averaged orbiting potential using phase jumps of the rotating field

“…The idea of the TOP was extended to an asymmetric triaxial TOP trap developed by Ref. [15] and used by other groups [17,18]. A number of other variations were introduced: In many cases, it turns out to be convenient to switch on the TOP after a preparative stage of cooling in a conventional static trap such as a magnetic quadrupole trap (see, e.g., Ref.…”

“…Following the achievement of the first BEC [2], the use of the axially symmetric TOP was described theoretically in Refs. [8][9][10][11][12][13] and explored experimentally by other groups [14][15][16][17][18][19] to study properties of the BEC. The idea of the TOP was extended to an asymmetric triaxial TOP trap developed by Ref.…”