EXOTICPHASES4QIT · Exotic quantum phases in graphene and other modern nanomaterials - physical foundation for quantum information technology

Exotic quantum phases in graphene and other modern nanomaterials - physical foundation for quantum information technology

The project addresses the problem of existence and properties of novel quantum phases of matter, fascinating from purely scientific perspective and of enormous potential impact in the field of quantum information technology. This problem is married with the new possibilities offered only recently by the still rapidly improving understanding and technology of graphene. The research of the exotic quantum phases and graphene nanostructures falls into the main stream of condensed matter physics and has built on the knowledge, experience, and collaboration gained or established during the Researcher’s preceding Marie Curie IEF project. The main research GOAL is understanding of exotic quantum matter, leading to its realization in graphene, with possible application in quantum information. The WORK carried out within the project falls into the following categories: (1) Implementation and optimization of tight-binding codes for the calculations of single-electron spectra of graphene nanostructures of arbitrary size and shape; (2) Optimization of previously developed exact-diagonalization codes, for accurate modelling of correlation effects in interacting many-electron systems in fractional quantum Hall effect, graphene nanostructures, etc.; (3) Calculations of electronic structure and correlation effects in graphene nanoislands of particular shape and type of edge; (4) Calculations of many-electron spectra on “Haldane sphere” (finite/computable model for condensation of a two-dimensional electron gas into a quantum liquid under strong magnetic field). Here, particularly important has been development of “composite fermion” diagonalization method utilizing the particular dynamical symmetry of interacting electrons in strong magnetic field (it relies on emergence of “composite fermions” - bound states of electrons and many-electron vortices). The MAIN RESULTS of the project are: (1) Understanding of emergent magnetism in a class of graphene quantum dots; (2) Comparative studies of fractional quantum Hall effect in graphene and conventional semiconductors, revealing the role of pseudospin degeneracy and different interaction pseudopotentials; (3) Development of the “multi-partite composite fermion” model and its application to relevant fractional quantum Hall systems - including the proposed microscopic mechanism for emergence of non-Abelian quantum statistics; (4) Understanding of incompressibility of several fractional quantum Hall states at filling factor 3/8 and 4/11; (5) Identification of exclusion rules for “composite fermion excitons” allowing for extension of composite fermion description to excited bands of quantum Hall systems. These results can also be summarized more broadly as: (1) Exploration of magnetic properties of many-electron graphene nanostructures; (2) Comparison of fractional quantum Hall effect in graphene and conventional semiconductors; (3) Development of composite fermion theory for fractional quantum Hall systems with spin or pseudospin (relevant to graphene). The results have been presented in a series of 15 articles in leading physics journals (including 5 in Physical Review Letters) and also in 7 invited conference lectures. An important outcome is reintegration of the Researcher at Wroclaw University of Technology - after return from preceding MC IEF at Cambridge. The Researcher has established a group of (currently) 1 postdoc, 5 PhD students and 1 MSc student (and collaborated with several more who meanwhile left group) and reached position of Full Professorship. The PROJECT WEBPAGE is placed at: http://www.if.pwr.wroc.pl/~awojs/ExoticPhases4QIT.html

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