Title: The role of dispersion forces for matter-wave binary holography experiments.

Johannes Fiedler (UiB) presented a poster in contribution to the 2nd European Quantum Technologies Virtual Conference (EQTC 2021 – https://www.eqtc.org/), on 1 december 2021.

Abstract: Lithography is a commonly applied method to create and manipulate semiconductor devices. A further
decrease of the size can currently be reached by using extreme-ultraviolet (EUV) photolithography
that uses electromagnetic radiation with a wavelength of 13.5 nm that corresponds to an energy of
92eV [1]. The disadvantage of this method is the high energy transfer from the photons to the wafer.
The ability to pattern materials at ever-smaller sizes using photolithography is driving advances in
nanotechnology. When the feature size of materials is reduced to the nanoscale, individual atoms and
molecules can be manipulated to dramatically alter material properties. Extreme ultraviolet – a
next-generation lithography technology – can deliver even pattern sizes down to a few nanometer
resolutions. However, the secondary electron blurring from extreme-ultraviolet photons hinders the
creation of single-molecule patterns. An alternative approach is the use of matter waves which
reaches similar and even much smaller wavelengths with a lower amount of kinetic energy [2].
Lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative
to EUV lithography. The great advantage of atom lithography is that the kinetic energy of an atom is
much less than that of a photon for a given wavelength. Already in 1995, it was demonstrated
experimentally that binary holography can be used to form arbitrary patterns using metastable atoms
[2]. In binary holography, a pattern of holes is used to approximate a Fourier transform of the desired
target pattern. Recently, it was shown theoretically that binary holography with metastable atoms can
in principle be used to form arbitrary patterns with nanometer resolution [3]. However, this publication
did not include interaction effects between the mask and the metastable atoms. Here we present an
investigation of how the dispersion forces between the atoms and the mask affect the path of the
atoms through silicon nitride masks. It was theoretically shown that binary holography with metastable
atoms can in principle be used to form arbitrary patterns with nanometer resolution [3]. However,
recent experiments and theories on matter-wave diffraction experiments have demonstrated that the
dispersion forces play an important role in such systems, leading to a reduction of the transmission
area on the one hand [4] and a spatially dependent phase shift imprinted on the matter-wave upon
leaving the obstacles on the other hand [5]. Dispersion forces are caused by the ground-state
fluctuations of the electromagnetic field which typically result in an attractive force between the
constituents.