E-Mail IMAGE: The spatial intensity profile of a laser beam propagating in a nonlinear medium spontaneously becomes nonuniform due to the process of modulational instability. view more Credit: Institute for Basic Science We are most familiar with the four conventional phases of matter: solid, liquid, gas, and plasma. Changes between two phases, known as phase transitions, are marked by abrupt changes in material properties such as density. In recent decades a wide body of physics research has been devoted to discovering new unconventional phases of matter, which typically emerge at ultra-low temperatures or in specially-structured materials. Exotic "topological" phases exhibit properties that can only change in a quantized (step-wise) manner, making them intrinsically robust against impurities and defects.