Topological Phase Transition in non-Hermitian Quasicrystals

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Topological Materials

Background:

• Non-Hermitian systems present unique phenomena like the breakdown of bulk-boundary correspondence and the non-Hermitian skin effect.
• While topological properties of non-Hermitian lattices are studied, non-Hermitian quasicrystals remain largely unexplored.
• Topological order is being redefined by discoveries in non-Hermitian open classical and quantum systems.

Purpose of the Study:

• To investigate topological phases in non-Hermitian quasicrystals.
• To explore the role of parity-time (PT) symmetry in these systems.
• To propose a photonic realization for experimental verification.

Main Methods:

• A non-Hermitian extension of the Aubry-André-Harper model was developed to describe the quasicrystal.
• The study analyzed the metal-insulating phase transition at the PT symmetry breaking point.
• Topological nature of the transition was characterized using a winding number.

Main Results:

• Topological phases were identified in the non-Hermitian quasicrystal.
• A topological metal-insulating phase transition was discovered at the PT symmetry breaking point.
• The transition was successfully characterized by a winding number, confirming its topological origin.

Conclusions:

• Non-Hermitian quasicrystals host novel topological phases.
• The findings extend the understanding of topological order beyond Hermitian systems.
• A potential photonic experimental platform for non-Hermitian quasicrystals was proposed.