Observation of the spin Hall effect of light by a single-photon detector.

We use a single-photon detector to detect the spin Hall effect of light (SHEL) of a quasi-single-photon beam obtained in this Letter. The physics of the spin Hall effect and its quantum weak measurement method with a dimensionless pointer are elucidated through particle number representation. Our weak measurement scheme obviates the necessity of high-resolution single-photon array detectors. Consequently, we have successfully observed the spin Hall effect within a 20 ns temporal window using a position-resolution-independent single-photon detector with remarkably low-noise levels. The weak measurement of the dimensionless pointer presented in this Letter boosts both the detection accuracy and the response speed of the photonics spin Hall effect, thereby contributing significantly to fundamental theoretical research in spin photonics and precise measurements of physical property parameters.

Estimation of Kerr angle based on weak measurement with two pointers.

In this paper, we propose a weak measurement method using two pointers to estimate the magneto-optical Kerr angle, which is robust to ellipticity. The double pointers are the amplified displacement shift and intensity of the post-selected light beam, which are the conventional information carried by the light beam and can be directly output by a detector (such as a charge-coupled device). We demonstrate that the product of the double pointers is only related to the phase variation between two basic vectors and independent of the amplitude errors. In the measurement process, when there is an amplitude change or additional amplitude noise between two eigenstates, the product of two pointers is very useful in extracting phase information and shielding amplitude noise. In addition, the product of two pointers has a good linear relationship with the phase variation and a larger dynamic measurement range. This method is applied to measure the magneto-optical Kerr angle of NiFe film. The Kerr angle can be directly obtained using the product of the light intensity and the amplified displacement shift. This scheme is of great significance for the measurement of the Kerr angle of magnetic films.