Zone-plate focusing of Bose-Einstein condensates for atom optics and erasable high-speed lithography of quantum electronic components

TL;DR

This paper demonstrates that Fresnel zone plates can focus Bose-Einstein condensates sharply, enabling applications in atom optics and high-speed, erasable lithography of quantum electronic components with nanoscale precision.

Contribution

It introduces the use of solid surface zone plates for focusing Bose-Einstein condensates and explores their application in scalable, minimally invasive lithography of quantum electronic devices.

Findings

Zone plates can focus condensates despite inter-atomic repulsion.

Focusing preserves condensate coherence and is insensitive to quantum fluctuations.

Focused alkali atom deposition can locally deplete two-dimensional electron gases at nanoscales.

Abstract

We show that Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes. The focusing process compresses the condensate by orders of magnitude despite inter-atomic repulsion. Crucially, the focusing dynamics are insensitive to quantum fluctuations of the atom cloud and largely preserve the condensates' coherence, suggesting applications in passive atom-optical elements, for example zone plate lenses that focus atomic matter waves and light at the same point to strengthen their interaction. We explore transmission zone-plate focusing of alkali atoms as a route to erasable and scalable lithography of quantum electronic components in two-dimensional electron gases embedded in semiconductor nanostructures. To do this, we calculate the density profile of a two-dimensional electron gas immediately below a patch of alkali atoms deposited on the surface of the nanostructure by zone-plate focusing. Our results reveal that surface-induced polarization of only a few thousand adsorbed atoms can locally deplete the electron gas. We show that, as a result, the focused deposition of alkali atoms by existing zone plates can create quantum electronic components on the 50 nm scale, comparable to that attainable by ion beam implantation but with minimal damage to either the nanostructure or electron gas.