Counting intrinsic localized modes in an antiferromagnet

An experimental investigation of frequency locking intrinsic localized modes (ILMs) in an atomic lattice system is reported. The authors demonstrate that a nonlinear four wave mixing measurement is the most sensitive detection method for studying these locked ILMs. The authors are able to count individual ILMs, and confirm the discrete nature of the locked nonlinear state. Future applications may lead to directed energy transfer and smart materials.