Topological degeneracy and pairing in a one-dimensional gas of spinless fermions
Name
PhysRevB.96.085133.pdf
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461.94 KB
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Author(s)
Altman, Ehud
Ruhman, Yehonatan
Date Issued
August 2017
Journal
Physical Review B
Publisher
American Physical Society
Citation
Ruhman, Jonathan and Ehud Altman. "Topological degeneracy and pairing in a one-dimensional gas of spinless fermions." Physical Review B 96, 8 (August 2017): 085133 © 2017 American Physical Society
Version
Final published version
Abstract
We revisit the low-energy physics of one-dimensional spinless fermion liquids, showing that with sufficiently strong interactions the conventional Luttinger liquid can give way to a strong-pairing phase. While the density fluctuations in both phases are described by a gapless Luttinger liquid, single fermion excitations are gapped only in the strong-pairing phase. Smooth spatial Interfaces between the two phases lead to topological degeneracies in the ground-state and low-energy spectrum of the density fluctuations. Using a concrete microscopic model, with both single-particle and pair hopping, we show that the strong-pairing state is established through emergence of a new low-energy fermionic mode. We characterize the two phases with numerical calculations using the density matrix renormalization group. In particular we find enhancement of the central charge from c=1 in the two Luttinger liquid phases to c=3/2 at the critical point, which gives direct evidence for an emergent critical Majorana mode. Finally, we confirm the existence of topological degeneracies in the low-energy phonon spectrum, associated with spatial interfaces between the two phases.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.96.085133
