Between order and disorder: ultracold atoms in a quasicrystalline optical lattice

Quasicrystals are long-range ordered and yet non-periodic. This interplay results in a wealth of intriguing physical phenomena, such as self-similarity, the inheritance of topological properties from higher dimensions, and the presence of non-trivial structure on all lengthscales. However, quasicrystalline materials are notoriously hard to synthesise, as defects and impurities may greatly alter their final microscopic composition. The field of quantum simulation with ultracold atoms offers a solution to this problem, namely the use of optical lattices – standing waves of light. Optical lattices are free of impurities and therefore ideally suited to study quasicrystals, enabling unprecedented access to observables that are unattainable in condensed matter systems. This study presents the first experimental realisation of a two-dimensional quasicrystalline potential for ultracold atoms, based on an eightfold symmetric optical lattice. Features pertaining to both ordered and disordered phases are observed, from sharp diffraction peaks in the matter-wave interference pattern, to a disorder-induced localised phase emerging at a critical lattice depth V_loc ~ 1.78 E_rec. The localised phase seems to be resilient against moderate interactions, which would make this the first experimental realisation of a 2D Bose glass.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2019

Author dc:creator

• Sbroscia, Matteo Stefano

Advisor dc:contributor.advisor

• Schneider, Ulrich

• Ultracold atoms
• Optical lattices
• Quasicrystals
• Aperiodic order

Statement dc:rights

• All third party material has been explicitly noted in the thesis and referenced accordingly.

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/23287a4c-38f2-41b6-8436-03b85d0b6568/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

en

Author Identifier

0000-0002-4101-5984

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/297701