Gapless symmetry-protected topological phase of fermions in one dimension

Anna Keselman and Erez Berg
Phys. Rev. B 91, 235309 – Published 8 June 2015

Abstract

We consider a one-dimensional, time-reversal-invariant system with attractive interactions and spin-orbit coupling. Such a system is gapless due to the strong quantum fluctuations of the superconducting order parameter. However, we show that a sharply defined topological phase with protected, exponentially localized edge states exists. If one of the spin components is conserved, the protection of the edge modes can be understood as a consequence of the presence of a spin gap. In the more general case, the localization of the edge states arises from a gap to single-particle excitations in the bulk. We consider specific microscopic models and demonstrate both analytically and numerically (using density matrix renormalization group calculations) that they can support the topologically nontrivial phase.

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  • Received 28 February 2015
  • Revised 15 May 2015

DOI:https://doi.org/10.1103/PhysRevB.91.235309

©2015 American Physical Society

Authors & Affiliations

Anna Keselman and Erez Berg

  • Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100

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Issue

Vol. 91, Iss. 23 — 15 June 2015

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