Anomalous Pairing Currents and a Second Topological Edge Channel in Bosonic Lattices

Abstract

We show that bosonic pairing opens a second chiral current channel on a 2D kagome lattice, absent from any particle-conserving model. From the continuity equation, we derive both a hopping current and an anomalous pairing current on the lattice, and predict chiral circulation in bulk-gapped phases with integer para-unitary Chern numbers, as well as a phase-sensitive leakage ratio, $Λ_{\cal I}$, for the pairing current around a defect. This ratio can be tuned from confined to strongly anomalous regimes at fixed topology. The two channels differ microscopically: the hopping current is sourced by the on-bond single-particle coherence, whereas the pairing current is sourced by the off-site anomalous coherence, whose spatial range is governed by the BdG pairing gap rather than by the single-particle gap. This separation produces distinct defect-induced signatures in real space, identifies a regime in which bulk topology and anomalous edge response coexist with no analogue in particle-conserving matter, and is directly testable in driven photonic lattices and superconducting-circuit arrays.