Lithography leads to highest resolution yet in magnetic atomic trap lattices

Quantum simulation poses to facilitate studying quantum systems that would otherwise be impossible to investigate in a controlled way. To date, most experiments have relied on laser techniques to trap ultracold atoms, restricted in resolution by the wavelength of light. New findings reveal a technique that provides a way to make magnetic lattice structures with even greater resolution to trap ultracold atoms for quantum simulation experiments.

La Rooij et al. demonstrated a new way to create magnetic atomic trap lattices in iron-platinum (FePt) thin films with significantly higher resolution than most atom trap lattices in use today. The group used molecular beam epitaxy and electron beam lithography (EBL) to produce 50-nanometer-thick permanent magnetic monocrystalline FePt films. The films were patterned to yield lattice structures down to roughly half the size of those in standard optical lattice traps, and smaller than wavelengths of visible light.

Decreasing the distance between atoms in a lattice trap allows them to tunnel more easily and allows one to do more complex quantum simulations. Iron-platinum thin films can yield magnetic lattices that can be etched into a various two-dimensional geometries, a freedom not found among optical lattices.

Using argon milling and EBL, a technique well developed for the semiconductor industry but new for iron-platinum thin films, the authors reach the 30-nanometer resolution that is required to make lattices with unit sizes of 5 micrometers down to 250 nanometers. The next plan is to use these lattices to study systems of trapped and interacting ultracold Rubidium atoms.

Source: “Deposition and patterning of magnetic atom trap lattices in FePt films with periods down to 200nm,” by A. L. La Rooij, S. Couet, M. C. van der Krogt, A. Vantomme, K. Temst, and R. J. C. Spreeuw, Journal of Applied Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5038165 .