Scientists observe ‘quasiparticles’ in classical systems

Quasiparticles — long-lived particle-like excitations — are a cornerstone of quantum physics, with famous examples such as Cooper pairs in superconductivity and, recently, Dirac quasiparticles in graphene. Now, researchers have discovered quasiparticles in a classical system at room temperature: a two-dimensional crystal of particles driven by viscous flow in a microfluidic channel. Coupled by hydrodynamic forces, the particles form stable pairs — a first example of classical quasiparticles, revealing deep links between quantum and classical dissipative systems.