Fingerprints of bosonic symmetry protected topological state in a quantum point contact

TL;DR

This paper investigates transport signatures in a quantum point contact to distinguish bosonic symmetry protected topological states from fermionic states in bilayer graphene, revealing unique phases and measurable fingerprints.

Contribution

It identifies specific transport signatures and phases that differentiate bosonic topological states from fermionic ones in bilayer graphene systems.

Findings

Discovery of a charge insulator/spin conductor phase for BSPT.

Identification of distinct transport phases for BSPT and QSH states.

Proposal of simple transport measurements to detect bosonic topological physics.

Abstract

In this work, we study the transport through a quantum point contact for bosonic helical liquid that exists at the edge of a bilayer graphene under a strong magnetic field. We identify "smoking gun" transport signatures to distinguish bosonic symmetry protected topological (BSPT) state from fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge insulator/spin conductor phase is found for BSPT state, while either charge insulator/spin insulator or charge conductor/spin conductor phase is expected for the two-channel QSH state. Consequently, a simple transport measurement will reveal the fingerprint of bosonic topological physics in bilayer graphene systems.