CONFERENCE PRESENTATIONS/SEMINAR TALKS
28 April 2022
Johannes Fiedler (UiB) presented nanolace at the Network Meeting of the Alexander von Humboldt Foundation, 27- 29 April 2022, University of Rostock, Germany
Title: The Role of Dispersion Forces for Matter-Wave Diffraction Experiments
Johannes FiedlerAbstract: Recent progress in matter-wave experiments led to technical applications, particularly for acceleration sensing, single-particle detectors, quantum microscopes or matter-wave lithography. Thus, they act on the nanometre length scale. Consequently, the quantised nature of the object is not neglectable. In particular, the quantum vacuum has to be taken into account. Hence, the interactions between the objects are dressed by the vacuum polarisability leading to the dispersion forces. The diffraction of matter waves is based on the wave-particle duality and has the advantage that waves with sub-nanometre wavelengths can be created and thus strongly increases the resolution compared to optical devices . However, the additional interactions between the matter-wave particles and the diffraction object dramatically influence the propagation of the wave . In this presentation, I will illustrate the impact of dispersion forces on the results of diffraction experiments and demonstrate possibilities for their manipulation to enhance the contrast for matter-wave lithography applications .  Brand, C., Fiedler, J., Juffmann, T., Sclafani, M., Knobloch, C., Scheel, S., Lilach, Y., Cheshnovsky, O., Arndt, M. (2015): A Green’s function approach to modeling molecular diffraction in the limit of ultra-thin gratings. In: Ann. Phys. (Berlin) 527, 580-591.  Gack, N., Reitz, C., Hemmerich, J.L., Könne, M., Bennett, B., Fiedler, J., Gleiter, H., Buhmann, S.Y., Hahn, H., Reisinger, T. (2020): Signature of Short-Range van der Waals Forces Observed in Poisson Spot Diffraction with Indium Atoms. In: Phys. Rev. Lett. 125, 050401.  Fiedler, J., Holst. B. (2022): An atom passing through a hole in a dielectric membrane: impact of dispersion forces on mask-based matter-wave lithography. In: J. Phys. B: At. Mol. Opt. Phys. 55, 025401.
01 December 2021
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 . 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 . 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 . 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 . 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 . 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  and a spatially dependent phase shift imprinted on the matter-wave upon leaving the obstacles on the other hand . Dispersion forces are caused by the ground-state fluctuations of the electromagnetic field which typically result in an attractive force between the constituents.
21 July 2021
The role of dispersion forces in matter-wave scattering experiments
Johannes Fiedler (UiB) presented a contribution to the FOMO lecture series (Lectures on Matter-Wave Interferometry) on July 21st 2021.Abstract: Dispersion forces, such as van der Waals forces between neutral particles or Casimir-Polder forces between neutral particles and dielectric surfaces, are caused by the ground-state fluctuations of the electromagnetic field. They can be understood via an exchange of virtual photons that are generated as a dipole response of the particle due to the vacuum fluctuation of the field surrounding it. These resulting forces are weak for large separations and dramatically increase with decreasing distances. To this end, in matter-wave scattering experiments, where the beam particles reach close distances to the diffracted object, which is typical in the order of a few nanometers, these forces dominate the interaction and have a large impact on the experimental results. In this talk, we will shortly introduce these forces and illustrate their impact on the diffraction of particle beams from porous materials. This is of particular relevance for metastable atom lithography with binary holography masks, currently pursued in the FET-Open project Nanolace. Link to the abstract: https://www.matterwaveoptics.eu/fomo2021/contributed-talks/fomo2021-abstract/fiedler-johannes-the-role-of-dispersion-forces-in-matter-wave-scattering-experiments/
21 July 2021
The NanoLace project: Grid-based holograms for matter waves lithography
Veronica Perez (NTNU) presented a contribution to the FOMO lecture series (Lectures on Matter-Wave Interferometry) on July 21st 2021.Abstract: Grid-based binary holography (GBH) is an attractive method for patterning with light or matter waves. It is an approximate technique in which different holographic masks can be used to produce similar patterns. Mask-based pat- tern generation is a critical and costly step in microchip production. The next- generation extreme ultraviolet- (EUV) lithography instruments with a wave- length of 13.5 nm are currently under development. In principle, this should allow patterning down to a resolution of a few nanometers in a single expo- sure. However, lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative to EUV lithography. The great advan- tage of atom lithography is that the kinetic energy of an atom is much less than that of a photon for the same wavelength. Until now, however, no method has been available for making masks for atom lithography that can produce arbitrary, high-resolution patterns; to achieve this is the aim of the NanoLace project. Here we present the resolution that can be achieved when making binary masks to create patterns in a target plane close to the mask with the use of an atom source. Through simulations, we investigate the diffraction and ideal size of the patterns formed by holographic masks using beams of room temperature metastable helium atoms. in an experimental setup. Our calculations are now being extended to consider all experimental key features. Link to the abstract: https://www.matterwaveoptics.eu/fomo2021/contributed-talks/fomo2021-abstract/simonsen-veronica-p-the-nanolace-project-grid-based-holograms-for-matter-waves-lithography/
09 March 2021
Nanolace at the Innovation Norway Launch
Project Coordinator Bodil Holst presented Nanolace at the Innovation Norway Launch of the Horizon Europe - Pillar III Innovation EuropeThe meeting took place as a virtual event on 9 march 9.00-11.00, with participation of the Norwegian ministers for research and higher education Henrik Aasheim and the minister of Trade and Industry Iselin Nybø https://www.innovasjonnorge.no/no/tjenester/arrangementer/kick-off-for-horisont-europas-innovasjonspilar/
18 September 2020
22 February 2022
An atom passing through a hole in a dielectric membrane: impact of dispersion forces on mask-based matter-wave lithography
Johannes Fiedler and Bodil Holst 2022 J. Phys. B: At. Mol. Opt. Phys. 55 025401
AbstractFast, large area patterning of arbitrary structures down to the nanometre scale is of great interest for a range of applications including the semiconductor industry, quantum electronics, nanophotonics and others. It was recently proposed that nanometre-resolution mask lithography can be realised by sending metastable helium atoms through a binary holography mask consisting of a pattern of holes. However, these first calculations were done using a simple scalar wave approach, which did not consider the dispersion force interaction between the atoms and the mask material. To access the true potential of the idea, it is necessary to access how this interaction affects the atoms. Here we present a theoretical study of the dispersion force interaction between an atom and a dielectric membrane with a hole. We look at metastable and ground state helium, using experimentally realistic wavelengths (0.05–1 nm) and membrane thicknesses (5–50 nm). We find that the effective hole radius is reduced by around 1–7 nm for metastable helium and 0.5–3.5 nm for ground-state helium. As expected, the reduction is largest for thick membranes and slow atoms.
28 April 2021
Atomtronic Matter-Wave Lensing
Saurabh Pandey, Hector Mas, Georgios Vasilakis, and Wolf von Klitzing
Phys. Rev. Lett. 126, 170402 – Published 28 April 2021Abstract: In this Letter, we demonstrate magnetogravitational matter-wave lensing as a novel tool in atom-optics in atomtronic waveguides. We collimate and focus matter waves originating from Bose-Einstein condensates and ultracold thermal atoms in ring-shaped time-averaged adiabatic potentials. We demonstrate “delta-kick cooling” of Bose-Einstein condensates, reducing their expansion energies by a factor of 46 down to 800 pK. The atomtronic waveguide ring has a diameter of less than one millimeter, compared to other state-of-the-art experiments requiring zero gravity or free-flight distances of ten meters and more. This level of control with extremely reduced spatial requirements is an important step toward atomtronic quantum sensors. Synopsis
15 June 2020
Article about Nanolace in Gemini, a Norwegian magazine on research news published by NTNU and Sintef. https://gemini.no/2020/06/fremtidens-raskeste-datadingser-kan-fa-norsk-hjelp/
27 September 2019
Nanolace is cover story in the Norwegian magazine for professional electronics Elektronikk 11/2019, p. 1-12: Gjennombrudd ved UiB: 1 nanometer i sikte. http://viewer.zmags.com/publication/1a09e128#/1a09e128/1