Author(s):

Authors: Gil Young Cho, Rodrigo Soto-Garrido, Eduardo Fradkin

We show that the pair-density-wave (PDW) superconducting state emergent in

extended Heisenberg-Hubbard models in two-leg ladders is topological in the

presence of an Ising spin symmetry and supports a Majorana fermion zero mode at

an open boundary. The state is similar to a conventional finite-momentum paired

state in that the order parameter is a charge-$2e$ field carrying finite

momentum. However, the order parameter here is a {\it quartic} electron

operator and conventional mean-field theory cannot be applied to study this

state. Beyond mean-field theory, we use bosonization to show that the

one-dimensional and quasi-one-dimensional pair-density-wave states have the

Majorana fermions zero modes at the boundary, and also at certain lattice

defects. Thus the superconducting states are exotic topological phases

supporting Majorana fermions with finite-momentum pairing fields and

charge-$4e$ superconductivity.

link to article (opens in new tab)

## Recent Comments