Bulk-Boundary Correspondence in Point-Gap Topological Phases.

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Topological Materials

Background:

• Non-Hermitian systems exhibit unique topological properties, including line-gap and point-gap topology.
• The bulk-boundary correspondence, a key principle in Hermitian topological phases, was unclear for point-gap topology.

Purpose of the Study:

• To establish the bulk-boundary correspondence for point-gap topology in non-Hermitian systems.
• To investigate the role of boundary conditions on topological properties.

Main Methods:

• Analysis of point-gap topology under open boundary conditions.
• Utilizing real space topological invariants and K theory.
• Classification of open boundary point-gap topology with symmetry.

Main Results:

• The bulk-boundary correspondence for point-gap topology in non-Hermitian systems is established.
• Point-gap topology under open boundary conditions can differ from periodic boundary conditions.
• Nontrivial open boundary topology leads to robust and exotic surface states.

Conclusions:

• This work clarifies the bulk-boundary correspondence in non-Hermitian point-gap topology.
• The findings are crucial for understanding topological phenomena in open quantum systems.
• Robust surface states arise from non-trivial open boundary topology.