# Synopsis: Downsizing Optical Lattices

Field patterns produced near nanoparticles could allow closely spaced traps for ultracold atoms.

Optical lattices formed by interfering laser beams provide a highly controllable test bench for trapping many atoms at once and studying their interactions. Because of diffraction, however, the wavelength of the trapping light limits how close the atoms can get to one another, and thus the achievable atomic density. As reported in Physical Review Letters, Michael Gullans, at Harvard University, and colleagues propose a way to overcome this limitation with subwavelength confinement of light produced by nanoplasmonic structures.

In the near field of a nanoparticle (i.e., at the distance of less than about one wavelength of a propagating wave), collective electron oscillations called plasmons can concentrate the electromagnetic field in regions much smaller than its wavelength. Gullans et al. show theoretically that the interference of an incident wave with the dipolar field it induces in a metallic particle creates a trapping region along the polarization direction of the field. In the case of silver nanospheres, slightly tuning the incident light to the blue side of an atomic resonance in rubidium should cause an atom to cling to the sphere. Arrays of nanoparticles could therefore act as anchors for an ordered lattice of ultracold atoms.

The authors suggest that with their proposed method, lattice spacings could be reduced by about an order of magnitude, from $500$ nanometers down to less than $60$ nanometers. Should experimentalists realize such nanoplasmonic lattices in the lab, the increased atomic density would allow the exploration of new regimes of dense, ultracold quantum matter. – David Voss

### Announcements

More Announcements »

## Previous Synopsis

Particles and Fields

Graphene

## Related Articles

Atomic and Molecular Physics

### Viewpoint: Bose Polarons that Strongly Interact

Researchers have used impurities within a Bose-Einstein condensate to simulate polarons—electron-phonon combinations in solid-state systems. Read More »

Atomic and Molecular Physics

### Synopsis: Taking Pictures with Single Ions

A new ion microscope with nanometer-scale resolution builds up images using single ions emitted one at a time from an ion trap. Read More »

Atomic and Molecular Physics

### Viewpoint: Squeezed Light Reengineers Resonance Fluorescence

By bathing a superconducting qubit in squeezed light, researchers have been able to confirm a decades-old prediction for the resulting phase-dependent spectrum of resonance fluorescence. Read More »