Toroidal optical dipole grating

Jochen Arlt, Kishan Dholakia, M. E. J. Friese +2 more

Ewan M. Wright, Jochen Arlt, Kishan Dholakia

We theoretically investigate the use of red-detuned Laguerre-Gaussian (LG) laser beams of varying azimuthal mode index for producing toroidal optical dipole traps in two-dimensional atomic Bose-Einstein condensates. Higher-order LG beams provide deeper potential wells and tighter confinement for a fixed toroid radius and laser power. Numerical simulations of the loading of the toroidal trap from a variety of initial conditions are also given.

Galina A. Nemova

Xuan-Qian Bao, Xue-Dong Tian, Dongxiao Li +1 more

We propose a theoretical scheme for dipole exchange-induced grating (DEIG) based on a hybrid coherent atomic system. The system consists of an ultra-cold rubidium ( 87 Rb) atomic ensemble and movable Rydberg spin atoms. The optical response of the grating appears as a superposition of three- and four-level configurations, which is similar to the cooperative optical nonlinearity caused by the dipole blockade effect. The far-field diffraction properties of the cooperative optical nonlinear grating are tuned by the probe field (intensity and photon statistics). However, our Rydberg atomic grating uniquely responds to the spatial positions of spin atoms, which offers a novel approach to dynamically control electromagnetically induced gratings (EIG).

Kai Xiang Lee, Vincent Mancois, Kelvin Lim +1 more

In addition to electric and magnetic multipoles, the expansion of current density also yields toroidal terms, a lesser-known family of multipoles. A recent proposal, I. Kuprov $\textit{et al.}$, Science Adv. 8 abq6751 (2022), explores the possibility of a direct observation of optical toroidal transitions in hydrogen and alkali atoms in the presence of a large magnetic field that decouples the spin and the angular momentum of the electron. However, the difficulty of observing these transitions against the nearby electric dipole (E1) transitions were underestimated because of extra admixture coming from diamagnetic coupling. Here, we revisit the toroidal coupling in atoms, taking diamagnetic contribution into account, and discuss the technical challenges of observing toroidal coupling in atomic physics. We show that toroidal transition should be searched in transitions with low principal quantum numbers. The remaining strong electric-dipole contribution could be removed using an appropriate differential measurement.

George M. Brooke, T. Takekoshi, Brian M. Patterson +1 more