Date/Time Date(s) - 30/09/202610:30 am - 11:30 am
BSB 108
Dr. Zhi-Feng Huang Professor Wayne State University
Title: Matter becomes active by nonreciprocity: A field-theoretical study Abstract:
Although Newton’s third law of reciprocity holds for all fundamental interactions in nature and also for effective interactions in equilibrium or near-equilibrium systems, the breaking of it has been found in various systems out of equilibrium particularly with components interacting effectively through media. Examples range from complex plasma, artificial colloidal and robotic materials, to biological and living matters such as humans, birds, fishes, starfish embryos, bacteria, microalgae, and other microorganisms. Nonreciprocity also occurs in systems characterized by non-Hermitian dynamical matrix, with the emergence of nonreciprocal phase transitions. In this talk I will discuss some of our recent efforts addressing the intriguing phenomenon of matter becoming active by nonreciprocity, in particular the nonequilibrium processes of active pattern formation, crystallization with odd elasticity, and defect self-dynamics induced by force or torque nonreciprocity. Two types of nonreciprocal, nonpotential systems are examined, including systems subjected to nonconservative transverse forces, which give rise to nonreciprocal torques and odd elastic responses, and systems governed by vision-cone type force interactions, leading to rich dynamics of active chiral patterns breaking parity-time (PT) symmetry during nonreciprocal phase transitions. Our focus is on a field-theoretical study to understand and predict these phenomena and their underlying mechanisms, through the development of continuum field models incorporating the fundamental physics of interparticle interactions, chirality, and symmetry breaking. The theories and predictions can be applied to a variety of biological and artificial active matter systems governed by nonreciprocity.