Test of the He-McKellar-Wilkins topological phase with atoms in high Rydberg states

The He-McKellar-Wilkins (HMW) topological phase, associated with the propagation of an electric dipole in a magnetic field [1,2], is an analogue of the Aharonov-Bohm phase for a charged particle propagating about a line of magnetic flux [3]. The first observation of the HMW phase was made by atom interferometry with cold ground-state lithium, but was limited to 27 mrad because of the comparatively small static electric dipole polarizability of the atoms [4]. Here, we report the observation of HMW phases of up to 2π rad in experiments with helium atoms in high Rydberg states. This work takes advantage of the large induced static electric dipole moments, in excess of 10000 D, of the 1s56s ³S₁ and 1s57s ³S₁ Rydberg states in helium. The experiments were performed by two-photon Ramsey interferometry in crossed electric and magnetic fields, and represent the first common-path observation of the HMW phase. The large HMW phases measured, open new opportunities to exploit effects of geometric phases in Rydberg-atom and -molecule optics and interferometry [4].

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[2] M. Wilkens, Phys. Rev. Lett. 72, 5 (1994)

[3] Y. Aharonov and A. Bohm, Phys. Rev. 115, 485 (1959)

[4] S. Lepoutre, A. Gauguet, G. Trénec, M. Büchner, and J. Vigué, Phys. Rev. Lett. 109, 120404 (2012)