Topological states in a one-dimensional fermi gas with attractive interaction

Jonathan Ruhman, Erez Berg, Ehud Altman

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

We describe a novel topological superfluid state, which forms in a one-dimensional Fermi gas with Rashba-like spin-orbit coupling, a Zeeman field, and intrinsic attractive interactions. In spite of total number conservation and the presence of gapless excitations, Majorana-like zero modes appear in this system and can be linked with interfaces between two distinct phases that naturally form at different regions of the harmonic trap. As a result, the low lying collective excitations of the system, including the dipole oscillations and the long-wavelength phonons are all doubly degenerate. While backscattering from point impurities can lead to a splitting of the degeneracies that scales algebraically with the system size, the smooth confining potential can only cause an exponentially small splitting. We show that the topological state can be uniquely probed by a pumping effect induced by a slow sweep of the Zeeman field from a high initial value down to zero. The effect is expected to be robust to introducing a finite temperature as long as it is much smaller than the interaction induced single particle gap in the final state of the sweep.

Original languageEnglish
Article number100401
JournalPhysical Review Letters
Volume114
Issue number10
DOIs
StatePublished - 13 Mar 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 American Physical Society.

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