Start date
Betweenand

# Proposal of a Quantum Phase Transition in 3D Dirac-Weyl topological semimetals: qubit storage on the grounds of bound states in the continuum

 Grant number: 18/09413-0 Support type: Regular Research Grants Duration: October 01, 2018 - September 30, 2020 Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics Principal researcher: Antonio Carlos Ferreira Seridonio Grantee: Antonio Carlos Ferreira Seridonio Home Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

This project proposes a Quantum Phase Transition (QPT) in 3D Dirac-Weyl semimetals with adatoms. Particularly for the graphene monolayer hosting a pair of adatoms collinear with the center of a hexagonal cell, A.C. Seridonio et al have shown in Phys. Rev. B 92 045409 (2015) that the system pseudogap with cubic scaling on energy, namely $\Delta\propto|\varepsilon|^{3},$ gives rise to spin-degenerate bound states in the continuum (BICs). These BICs are promising platforms for qubit storage, which were already verified in the ongoing FAPESP project (2015/23539-8) by means of the papers Phys. Rev. B 93 165116 (2016) and Phys. Rev. B 93 125426 (2016) for Majorana Fermions-based setups. Moreover, in the context of graphene, but for adatoms locally coupled to a single carbon of the sheet, the pseudogap scales linearly with energy and prevents the formation of BICs. However, effects of non-local coupling due to a Fano factor of interference $q_{0},$ which in the graphene monolayer is tunable by changing the slope of the Dirac cones, open the possibility for the emergence of magnetic BICs, as deeply discussed by A.C. Seridonio et al in Phys. Rev. B 92 245107 (2015) and Phys. Rev. B 94 205119 (2016). For graphene system near the critical point $q_{0}\approx q_{c},$ A.C. Seridonio et al have found that the system undergoes a QPT, being characterized by a magnetic phase. In this way, switching on $(q_{0}>q_{c})$ or off \$(q_{0}