Majorana edge state in a number-conserving Fermi gas with tunable p-wave interaction

TL;DR

This paper demonstrates the existence of Majorana edge states in a number-conserving 1D spinless Fermi gas with tunable p-wave interactions, using a simple setup that does not require spin-orbit coupling or multi-chain configurations.

Contribution

It introduces a novel scheme for realizing Majorana fermions in a single-chain, number-conserving cold atom system with tunable p-wave interactions, analyzed via DMRG.

Findings

Majorana phase identified over a wide parameter range

Strong edge-edge correlations demonstrate topological nature

Majorana phase remains stable against atom losses

Abstract

The remarkable properties and potential applications of Majorana fermions have led to considerable efforts in recent years to realize topological matters that host these excitations. For a number-conserving system, there have been a few proposals, using either coupled-chain models or multi-component system with spin-orbit coupling, to create number fluctuation of fermion pairs in achieving Majorana fermion. In this work, we show that Majorana edge states can occur in a spinless Fermi gas in 1D lattices with tunable $p$-wave interaction. This is facilitated by the conversion between a pair of (open-channel) fermions and a (close-channel) boson, thereby allowing the number fluctuation of fermion pairs in a single chain. This scheme requires neither spin-orbit coupling nor multi-chain setup and can be implemented easily. Using the density-matrix-renormalization-group method, we have identified the Majorana phase in a wide range of parameter regime as well as its associated phase transitions. The topological nature of the Majorana phase manifests itself in a strong edge-edge correlation in an open chain that is robust against disorder, as well as in a non-trivial winding number in the bulk generated by using twisted boundary condition. It is also shown that the Majorana phase in this system can be stable against atom losses due to few-body collisions on the same site, and can be easily identified from the fermion momentum distribution. These results pave the way for probing the intriguing Majorana physics in a simple and stable cold atoms system.