Ultrasensitive measurement of angular rotations via a Hermite–Gaussian pointer

Exploring high sensitivity on the measurement of angular rotations is an outstanding challenge in optics and metrology. In this work, we employ the m n -order Hermite–Gaussian (HG) beam in the weak measurement scheme with an angular rotation interaction, where the rotation information is taken by another HG mode state completely after the post-selection. By taking a projective measurement on the final light beam, the precision of angular rotation is improved by a factor of 2 m n + m + n . For verification, we perform an optical experiment where the minimum detectable angular rotation improves 15 -fold with HG55 mode over that of HG11 mode, and achieves a sub-microradian scale of the measurement precision. Our theoretical framework and experimental results not only provide a more practical and convenient scheme for ultrasensitive measurement of angular rotations but also contribute to a wide range of applications in quantum metrology.