Experimental Observation of Toroidal Dipole Modes in All‐Dielectric Metasurfaces

Experimental observation of localized modes in a dielectric square resonator.

We investigated the frequency spectra and field distributions of a dielectric square resonator in a microwave experiment. Since such systems cannot be treated analytically, the experimental studies of their properties are indispensable. The momentum representation of the measured field distributions shows that all resonant modes are localized on specific classical tori of the square billiard. B...

Experimental Observation of Surface and Interface Modes by Light Scattering

Experimental observation of high-order quantum accelerator modes.

Using a freely falling cloud of cold cesium atoms periodically kicked by pulses from a vertical standing wave of laser light, we present the first experimental observation of high-order quantum accelerator modes. This confirms the recent prediction by Fishman, Guarneri, and Rebuzzini [Phys. Rev. Lett. 89, 084101 (2002)]]. We also show how these accelerator modes can be identified with the stabl...

Observation of dipole-dipole interaction in a degenerate quantum gas.

We have investigated the expansion of a Bose-Einstein condensate of strongly magnetic chromium atoms. The long-range and anisotropic magnetic dipole-dipole interaction leads to an anisotropic deformation of the expanding chromium condensate which depends on the orientation of the atomic dipole moments. Our measurements are consistent with the theory of dipolar quantum gases and show that a chro...

Observations of Coupled Spheroidal and Toroidal Modes

In low-frequency seismic spectra the Coriolis force theoretically causes quasi-degenerate coupling of spheroidal and toroidal modes whose spherical harmonic degrees differ by unity and whose frequencies are close. It has been found that the coupling causes clearly observable effects on seismic spectra below 3.0 mHz. Many fundamental toroidal modes have a spheroidal component and vice versa. For...