Pair of Exceptional Points in a Microdisk Cavity under an Extremely Weak Deformation

Area of Science:

• Quantum physics
• Wave systems
• Optical cavities

Background:

• Open quantum and wave systems exhibit non-Hermitian degeneracy known as exceptional points.
• Exceptional points are states where both energy levels and eigenstates coalesce.
• These phenomena are crucial for understanding complex system behaviors.

Purpose of the Study:

• To demonstrate the emergence of exceptional points in optical microdisk cavities.
• To explain the underlying mechanism of this degeneracy using semiclassical theory.
• To investigate the characteristics and origins of these exceptional points.

Main Methods:

• Theoretical analysis using semiclassical theory of dynamical tunneling.
• Numerical or experimental investigation of optical microdisk cavities with weak boundary deformation.
• Mode analysis to identify symmetry classes and degeneracy.

Main Results:

• Exceptional points are shown to appear in optical microdisk cavities even with extremely weak boundary deformation.
• The semiclassical theory of dynamical tunneling provides an explanation for the observed degeneracy.
• Exceptional points appear in nearly degenerated pairs due to different mode symmetry classes.
• A local chirality of modes at exceptional points is linked to Poynting vector vortex structures.

Conclusions:

• Exceptional points can be realized in practical optical systems like microdisk cavities.
• Dynamical tunneling is a key mechanism for understanding non-Hermitian degeneracies in such systems.
• The findings offer insights into mode chirality and energy flow in optical systems near degeneracy.