Title Anyons, Zitterbewegung and dynamical phase transitions in topologically nontrivial systems
Title (croatian) Anyoni, Zitterbewegung i dinamički fazni prijelazi u topološki netrivijalnim sustavima
Author Frane Lunić
Mentor Hrvoje Buljan (mentor)
Mentor Dario Jukić (komentor)
Committee member Karlo Lelas (predsjednik povjerenstva)
Committee member Robert Pezer (član povjerenstva)
Committee member Hrvoje Buljan (član povjerenstva)
Granter University of Zagreb Faculty of Science (Department of Physics) Zagreb
Defense date and country 2022-07-07, Croatia
Scientific / art field, discipline and subdiscipline NATURAL SCIENCES Physics
Universal decimal classification (UDC ) 53 - Physics
Abstract Nontrivial topology in physical systems is the driving force behind many interesting phenomena. Notably, phases of matter must be classified in part by their topological properties. Phases with topological (nonlocal) order, such as the fractional quantum Hall effect (QHE), can support anyonic excitations obeying fractional statistics with potential application in topological quantum computing. States lacking intrinsic topological order can still belong to topological phases, provided certain symmetries are imposed. On their own, these symmetry-protected phases do not support anyons, but they can still have other interesting features, such as protected boundary states. In this thesis we present an original research into several topologically nontrivial systems. First, we present the experimental and theoretical results on light propagation in the valley modes of inversion-symmetry broken honeycomb lattices (HCL). We find that a rotating spiral pattern, leading to Zitterbewegung, arises in the intensity profile of the beam as a result of the nontrivial topology of the HCL valleys. Next, we present the numerical demonstration of dynamical topological phase transitions driven by nonlinearity of the photonic medium, which occur in soliton SSH lattices. The phase transitions, marked by the appearance of topological edge states in the band gap, occur due to the setup which enables continually changing relative values of the intracell and intercell soliton couplings. Finally, we propose a scheme for creating and manipulating synthetic anyons in a noninteracting system by perturbing it with specially tailored localized probes. The external probes are needed because noninteracting systems do not possess the kind of topological order required to support anyonic excitations. We start from a noninteracting 2D electron gas in a uniform magnetic field, which is in an integer QHE state, and introduce thin solenoids carrying a fractional magnetic flux. We present the solution for a suitable ground state, and demonstrate the fractional braiding statistics in the coordinates of the solenoids.
Abstract (croatian) U ovoj disertaciji proučavali smo više tema koje objedinjuje utjecaj topologije na fiziku sustava. Glavni cilj bio je prezentacija originalnih članaka [52,53,18], no pritom smo predstavili i neke bitnije teme vezane za topološku kvantnu materiju uključujući IQHE, FQHE, anyone i SPT faze. IQHE i FQHE, iako različiti, su povezani, a obje pojave su bitna pozadina za naše sintetičke anyone. Dok IQHE služi kao temelj za naš model, Laughlinove kvazičestice u FQHE-u daju inspiraciju za ideju perturbacije sustava lokaliziranim frakcijskim solenoidnim probama. U sklopu prezentacije prvog članka prikazali smo utjecaj netrivijalne topologije dolinskog stupnja slobode saćaste rešetke na propagaciju svjetla kroz fotonički kristal. Ovaj utjecaj se manifestira kroz pojavu „vorteks” komponente koja u interferenciji s "nevorteks" komponentom uzrokuje rotirajući spiralni uzorak u profilu intenziteta te s njim povezanu pojavu Zitterbewegunga. Ove pojave smo vidjeli u rezultatima eksperimenta i u teorijskim proračunima. U sljedećem dijelu predstavili smo rezultate numeričke studije evoluirajuće solitonske SSH rešetke koja je moguća zahvaljujući nelinearnosti fotoničkog medija. Uočili smo periodičku pojavu rubnih stanja u spektralnom procijepu s faznim profilom topoloških rubnih stanja koja signalizira topološke fazne prijelaze. Ovakvi topološki fazni prijelazi primjer su emergentne nelinearne topološke pojave. U posljednjem dijelu predlažemo realizaciju sintetičkih anyona perturbacijom neinteragirajućeg sustava posebnim lokaliziranim probama. Naši sintetički anyoni se razlikuju od emergentnih frakcijskih kvazičestica kakve se javljaju u sustavima poput FQHE-a, no realizacija ovog modela je poželjna jer bi njegov neabelovski pandan mogao biti podloga za topološka kvantna računala. Sustavi ultrahladnih atoma sa sintetičkim vektorskim potencijalima su obećavajuća platforma za ovu namjenu.
Keywords
Berry phase
Berry curvature
topology
topological quantum matter
photonics
Zitterbewegung
symmetry broken honeycomb lattice
valley degree of freedom
SSH model
optical solitons
nonlinearity
anyons
fractional statistics
topological quantum computation
quantum Hall effect
synthetic anyons
Keywords (croatian)
Berryjeva faza
Berryjeva zakrivljenost
topologija
topološka kvantna materija
fotonika
Zitterbewegung
saćasta rešetka s narušenom simetrijom
dolinski stupanj slobode
SSH model
optički solitoni
nelinearnost
anyoni
frakcijska statistika
topološko kvantno računanje
kvantni Hallov efekt
sintetički anyoni
Language english
URN:NBN urn:nbn:hr:217:171115
Promotion 2022
Study programme Title: Physics Study programme type: university Study level: postgraduate Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
Type of resource Text
Extent 106 str.
File origin Born digital
Access conditions Open access
Terms of use
Created on 2022-08-26 11:45:18