Non-Bloch-Band Collapse and Chiral Zener Tunneling

Non-Bloch-band theory describes bulk energy spectra and topological invariants in non-Hermitian
crystals with open boundaries, where the bulk eigenstates are squeezed toward the edges (skin effect).
However, the interplay of non-Bloch-band theory, skin effect, and coherent Bloch dynamics is so far
unexplored. In two-band non-Hermitian lattices, it is shown here that collapse of non-Bloch bands and skin
modes deeply changes the Bloch dynamics under an external force. In particular, for resonance forcing
non-Bloch-band collapse results in Wannier-Stark ladder coalescence and chiral Zener tunneling between
the two dispersive Bloch bands