Chirality of wave functions for three coalescing levels

TL;DR

This paper explores the unique chiral properties of wave functions near a three-level coalescence point, revealing how the distribution of level widths determines handedness and orientation in the system.

Contribution

It introduces the concept of chirality for wave functions at an EP3, extending the understanding of exceptional points beyond the well-studied two-level cases.

Findings

Wave functions near EP3 exhibit chiral behavior.

Handedness depends on the distribution of level widths.

Orientation in the plane is determined by the coalescence of three levels.

Abstract

The coalescence of three levels has particular attractive features. Even though it may be difficult to realise such event in the laboratory (three additional real parameters must be adjusted), to take up the challenge seems worthwhile. In the same way as the chiral behaviour of a usual EP can give a direction on a line, the state vectors in the vicinity of an EP3 provide an orientation in the plane. The distinction between left and right handedness depends on the distribution of the widths of the three levels in the vicinity of the point of coalescence.