  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.
