Giant pulling and pushing optical forces induced by a parity-time symmetric system

When particles interact with light, they can absorb momentum, leading to optical forces and torques that are widely used for manipulating microscopic objects. In this study, we demonstrate that a parity-time (PT) symmetric laser operating near and below the lasing threshold can generate giant optical pulling and pushing forces, surpassing conventional radiation pressure by several orders of magnitude. This remarkable enhancement arises from the spectral singularities of the PT-symmetric system, where both reflection and transmission coefficients diverge at real frequencies. The giant forces open up new possibilities for controlling micro- and nanoparticles through routing, trapping, and assembly.