Publications Daniel SCHNEIDER GRÜN

2026

Article

• D. Schneider Grün, L. Bellinato Giacomelli, A. Tashchilina, R. Donofrio, F. Borchers, T. Bland, M. J. Mark, F. Ferlaino Light-Assisted Collisions in Tweezer-Trapped Lanthanides, Phys. Rev. Research (2026-04-22), http://dx.doi.org/10.48550/arXiv.2506.05123 doi:10.48550/arXiv.2506.05123
  We present a quantitative investigation of one- and two-body light-mediated processes that occur to few erbium atoms in an optical tweezer, when exposed to near-resonant light. In order to study the intertwined effects of recoil heating, cooling, and light-assisted collisions, we develop a first-principles Monte Carlo algorithm that solves the coupled dynamics of both the internal and external degrees of freedom of the atoms. After validating our theoretical model against experimental data, we use the predictive power of our code to guide our experiment and, in particular, we explore the performance of different transitions of erbium for light-assisted collisions in terms of their efficiency and fidelity for single-atom preparation.

2024

Article

• D. Schneider Grün, S. White, A. Ortu, A. Di Carli, H. Edri, M. Lepers, M. J. Mark, F. Ferlaino Optical Tweezer Arrays of Erbium Atoms, Phys. Rev. Lett. 133 223402 (2024-11-26), http://dx.doi.org/10.1103/PhysRevLett.133.223402 doi:10.1103/PhysRevLett.133.223402
  We present the first successful trapping of single erbium atoms in an array of optical tweezers. Using a single narrow-line optical transition, we achieve deep cooling for direct tweezer loading, pairwise ejection, and continuous imaging without additional recoil suppression techniques. Our tweezer wavelength choice enables us to reach the magic trapping condition by tuning the ellipticity of the trapping light. Additionally, we implement an ultrafast high-fidelity fluorescence imaging scheme using a broad transition, allowing time-resolved study of the tweezer population dynamics from many to single atoms during light-assisted collisions. In particular, we extract a pair-ejection rate that qualitatively agrees with the semiclassical predictions by the Gallagher-Pritchard model. This Letter represents a promising starting point for the exploration of erbium as a powerful resource for quantum simulation in optical tweezers.

2022

Article

• G. Natale, T. Bland, Simon Gschwendtner, Louis Lafforgue, Daniel S. Grün, A. Patscheider, Manfred J. Mark, F. Ferlaino Bloch oscillations and matter-wave localization of a dipolar quantum gas in a one-dimensional lattice, Communications Physics 5 227 (2022-09-15), http://dx.doi.org/10.1038/s42005-022-01009-8 doi:10.1038/s42005-022-01009-8
  Three-dimensional quantum gases of strongly dipolar atoms can undergo a crossover from a dilute gas to a dense macrodroplet, stabilized by quantum fluctuations. Adding a one-dimensional optical lattice creates a platform where quantum fluctuations are still unexplored, and a rich variety of new phases may be observable. We employ Bloch oscillations as an interferometric tool to assess the role quantum fluctuations play in an array of quasi-two-dimensional Bose-Einstein condensates. Long-lived oscillations are observed when the chemical potential is balanced between sites, in a region where a macrodroplet is extended over several lattice sites. Further, we observe a transition to a state that is localized to a single lattice plane−driven purely by interactions−marked by the disappearance of the interference pattern in the momentum distribution. To describe our observations, we develop a discrete one-dimensional extended Gross-Pitaevskii theory, including quantum fluctuations and a variational approach for the on-site wavefunction. This model is in quantitative agreement with the experiment, revealing the existence of single and multisite macrodroplets, and signatures of a two-dimensional bright soliton.