Ultrasensitive probing of nematic order parameter via weak measurement

Nematic order parameter S is one of the most crucial material parameters of the nematic phase, which governs all of the material's anisotropic properties. The enhancement of its measurement precision has always been a great concern. In this Letter, a weak measurement scheme with a modified shift pointer is presented to achieve an ultrasensitive probe of S or the director's orientational angle θ. Using this scheme, we have demonstrated a real-time monitoring of the orientational process of cellulose nano-crystal molecules in solutions and measured the orientational direction of polymer nanowires. A typical precision on the order of 10−3 is achieved in the measurement of S and θ. Compared with the current existing techniques, the present scheme not only offers higher measurement precision but also maintains extreme cost-efficiency, thereby holding significance for the research of orientational materials and devices.