Directly to content
  1. Publishing |
  2. Search |
  3. Browse |
  4. Recent items rss |
  5. Open Access |
  6. Jur. Issues |
  7. DeutschClear Cookie - decide language by browser settings

Pattern Formation and Supersolid Sound Modes in a Driven Superfluid

Liebster, Nikolas Daniel

[thumbnail of Main_ArchiveVersion.pdf]
Preview
PDF, English
Download (15MB) | Terms of use

Citation of documents: Please do not cite the URL that is displayed in your browser location input, instead use the DOI, URN or the persistent URL below, as we can guarantee their long-time accessibility.

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.

Document type: Dissertation
Supervisor: Oberthaler, Prof. Dr. Markus
Place of Publication: Heidelberg
Date of thesis defense: 9 June 2025
Date Deposited: 18 Aug 2025 09:36
Date: 2025
Faculties / Institutes: The Faculty of Physics and Astronomy > Kirchhoff Institute for Physics
About | FAQ | Contact | Imprint |
OA-LogoDINI certificate 2013Logo der Open-Archives-Initiative