Two Beads, One Standing Wave: A Lab-Scale Time Crystal
NYU researchers demonstrate a classical time crystal using an acoustic standing-wave field to levitate and couple tiny polystyrene beads; through non-reciprocal scattering of sound, the beads self-sustain a temporal oscillation without external driving, making it the simplest possible time-crystal system and offering a macroscopic platform to study non-reciprocity. The findings are reported in Physical Review Letters.