Condensed-matter physicists have their own particle zoo – a menagerie filled with familiar and exotic quasiparticles including old favourites like holes and phonons, and newer additions such as surface plasma polaritons. Quasiparticles are excitations in a solid that behave like tiny particles and obey quantum mechanics. A phonon for example, is a quantized sound wave that propagates through a crystal.
Now Charles Tahan and colleagues at the Laboratory for Physical Sciences just outside Washington, DC have shown that the interaction between phonons and electronic excitations in certain semiconductors can be described in terms of a brand new quasiparticle called the phoniton.