Control spontaneous symmetry breaking of photonic chirality with reconfigurable anomalous nonlinearity
Spontaneous symmetry breaking in nonlinear systems provides a unified method to understand vastly different phenomena, ranging from Higgs mechanism  and superconductivity  to ecological stability  and genome generation . Spontaneous symmetry breaking is typically considered as the intrinsic property of nonlinear systems with fixed occurrence condition and property, as the form and magnitude of nonlinear interactions cannot be modified . Here, we report the development of reconfigurable Kerr optical nonlinearity to control spontaneous symmetry breaking. This is achieved through the interference between the intrinsic Kerr and cascaded second-order nonlinear processes . Anomalous Kerr effects including negative self-phase modulation and strength tuning between competing nonlinear processes have been demonstrated. With the reconfigurable Kerr nonlinearity, we realize the in-situ prohibition and facilitation of spontaneous symmetry breaking of photonic chirality. This work could empower the experimental study of spontaneous symmetry breaking in unexplored regimes and inspire the development of novel photonic functions.