While usual gapless points that are not geometrically defective i.e. Dirac points (Left column) possess only eigenvalues within [0, 1] (Bottom Left), defective exceptional points (Right column) also ...

Thermodynamic spontaneity—whether a reaction can go—can be measured by changes in either of two parameters: entropy or free energy.

This figure shows that for the superposition state of many EPL, they represent an anisotropic measurement characteristic depending on the long axis and short axis of the corresponding ellipse. The ...