Fig. 2: Schematic representation of the model and the phase diagram at the mean field level and beyond.
From: Quantum restoration of symmetry protected topological phases
a Schematic representation of the model, Eq. (3). The rectangular boxes denote the Cooper pair boxes. b Phase diagram of the Bogoliubov-de Gennes free-fermion Hamiltonian, Eq. (4): Δ breaks the symmetry protecting the free-fermion topology (cf Fig. 1b) so that topological and trivial phases may be adiabatically connected. TI and triv.I. represent topological and trivial insulator respectively. Note that there is a gap closure (as expected from standard SSH physics) at \(t={t}^{{\prime} }\) (for Δ = 0). c Schematic phase diagram of Eq. (3). Note the region exhibiting quantum restoration of symmetry protected topological (QRSPT) phase appears at small Δ and \(t < {t}^{{\prime} }\).
