eprintid: 36970
rev_number: 10
eprint_status: archive
userid: 9182
dir: disk0/00/03/69/70
datestamp: 2025-08-18 09:36:46
lastmod: 2025-08-18 09:37:04
status_changed: 2025-08-18 09:36:46
type: doctoralThesis
metadata_visibility: show
creators_name: Liebster, Nikolas Daniel
title: Pattern Formation and Supersolid Sound Modes in a Driven Superfluid
divisions: i-130700
adv_faculty: af-13
abstract: Systems driven far from equilibrium can show radically different properties from the same system at equilibrium. In some cases, new steady-states can emerge, enabling the application of theoretical frameworks typically developed in equilibrium. In this thesis, we discuss the emergence of self-stabilized, square lattice patterns in a Bose-Einstein condensate (BEC) with periodically modulated interactions. We show that despite the dynamical nature of the system, the patterned state displays Goldstone modes that are identical to those of supersolids, which are equilibrium superfluids with spontaneously arising periodic ordering.
We first provide a brief overview of the theoretical concepts underpinning the spontaneous emergence of the pattern, as well as its stabilization. We then present the experimental techniques used to observe the pattern, focusing mainly on tunable interactions and local control over the cloud using a digital micromirror device. Experimental results on the emergence of the structure are discussed, demonstrating that the pattern is truly a result of nonlinear phenomena far from equilibrium. We then turn towards explicit imprinting of lattices, which enables us to probe the phonon-phonon interactions that explain pattern stabilization. Beyond imprinting ideal lattices, we also explicitly instigate lattice and superfluid defects, observing their propagation. We identify two distinct speeds of sound for longitudinal excitations and a diffusive mode for transverse lattice deformations. We compare the extracted mode structure to a generic framework of superfluid smectics, extracting relevant hydrodynamic parameters of the system. Finally, we compare the dynamics of wavepackets to collective modes, finding good agreement.
date: 2025
id_scheme: DOI
id_number: 10.11588/heidok.00036970
own_urn: urn:nbn:de:bsz:16-heidok-369707
date_accepted: 2025-06-09
advisor: HASH(0x558b45a61b78)
language: eng
bibsort: LIEBSTERNIPATTERNFOR2025
full_text_status: public
place_of_pub: Heidelberg
citation:   Liebster, Nikolas Daniel  (2025) Pattern Formation and Supersolid Sound Modes in a Driven Superfluid.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/36970/1/Main_ArchiveVersion.pdf