Optics Express

Anomalous amplification in almost-balanced weak measurement for measuring spin Hall effect of light

Lan E Luo, Yu He, Xiong Liu, Zhaoxue Li, Pi Duan, Zhiyou Zhang

Published Feb 11, 2020• 13 citations

Abstract

In this paper, a method to measure the tiny spin splitting of the spin Hall effect of light (SHEL) using the almost-balanced weak measurement (ABWM) is presented. The ABWM technique uses two orthogonal post-selected states to record all of the information, which is a precise measurement method being different from the standard weak measurement (SWM). The theory model to describe the SHEL measurement based on ABWM is established. As results, the ABWM scheme has a larger amplification factor, reaching ∼105, which is nearly one order of magnitude higher than that of the SWM. When the post-selected angle is less than a certain value, the sensitivity and amplification factor of the ABWM scheme are higher than those of the SWM scheme, while the measurement precision and SNR of the ABWM technique are comparable to those of the SWM scheme. This research may have great potential for the precision metrology or sensing field based on the SHEL measurement.

DOI: 10.1364/oe.386017

Related papers

Weak value amplification of Geometric Spin Hall shift of light beam

Sumit Goswami, Nirmalya Ghosh, Mandira Pal +1 more

Geometric Spin Hall effect of light (SHEL) has attracted considerable attention because of the universality of this variant of the spin Hall shift and its independence on the light-matter interactions and materials properties. However, the magnitude of geometric SHEL is typically very small, in the sub-wavelength domain, making it difficult for direct experimental observation. Here, we have applied weak measurement schemes to amplify and faithfully observe the geometric SHEL. In our experiment, the input beam is pre-selected in linear polarization basis (p- or slinear polarization) and post selections are done at nearly orthogonal linear polarizations (small angle ϵ away from the exact orthogonal).This results in weak value amplification (~cotϵ) of the resulting shift of the beam centroid. Moreover, this process also leads to selective conversion of spatial to angular nature of geometric SHEL, which along with the weak value amplification leads to manifold amplification of the resulting SHEL, enabling its reliable experimental detection. A key feature of our weak measurement scheme is that both the weak perturbation (tiny geometric SHEL) and the post selection are done simultaneously by a single optical element, namely, a linear polarizer. The dependence of the weak value of the geometric SHEL on the pre and the post selection of polarization states in both linear and elliptical basis were also investigated in details. The specifics of the different weak measurement schemes, various intriguing experimental manifestations of the weak value amplified geometric SHEL, their analysis / interpretation via polarization operator based treatment of weak measurements is presented here.

SPIE NanophotonicsMay 4, 20180 citations

Complex signal measurement based on weak measurements

Lan E Luo, Tong Li, Tianchen Li +3 more

In the application of weak measurements, such as the estimation of magnetic parameters, the purely real weak coupling of standard weak measurement (SWM) does not correspond to the true physical parameters. To accommodate more complex application scenarios, we further explore three different weak measurement models in which both complex weak coupling and complex weak values coexist. This paper theoretically analyzes pointer variations and applicable ranges in SWM, double pointer weak measurement (DPWM), and almost-balanced weak measurement (ABWM) under specific conditions. Notably, only ABWM can successfully distinguish the real and imaginary components of weak values under complex weak-coupling conditions. While SWM and DPWM can also solve for weak values, they fail to obtain a unique and correct test value. The ABWM technique provides a higher sensitivity than SWM when measuring extremely small parameters. Furthermore, we apply ABWM to the magneto-optical Kerr effect measurement of a Ni-Fe film. This research deepens the understanding of weak measurement techniques and introduces new methods for multiparameter measurements.

Optics ExpressApr 29, 20252 citations

Optimal pre- and post-selections of weak measurements for precision parameter estimation

Xiong Liu, Xiaodong Qiu, Linguo Xie +4 more

Weak measurements, which offer a significant signal enhancement with pre- and post-selections, have proven to be powerful for precision metrology. However, the measured precision of the parameter of interest is always limited by the post-selection-induced probe loss, especially in the presence of technical noise. In this paper, we investigate the optimal pre- and post-selections of weak measurements for precision metrology in the presence of technical noise. While weak measurements apply more generally, we experimentally measure the spin splitting induced by the spin Hall effect of light (SHEL) to approach this issue. The highest measured precision of the spin splitting can be obtained with the post-selected state in the nonlinear intermediate regime. Surprisingly, the pre- and post-selections for the largest weak-value amplification are incapable of estimation of the spin splitting, since the amplified shift is independent of the spin splitting. Our results are not restricted to the SHEL and could be applied to other parameter estimations with weak measurements.

Journal of Applied PhysicsMay 28, 20175 citations

Amplifying a Tiny Optical Effect

Kevin J. Resch

How do you measure a transverse shift of a light beam to within a nanometer? Recently, physicists predicted (1) that light could experience such a shift similar to what happens to electrical currents in semiconductors through the spin Hall effect (2–4). On page 787 of this issue, Hosten and Kwiat (5) use “weak measurement,” a controversial procedure from the foundations of quantum mechanics, to amplify this spin Hall effect in light (SHEL) rather than detecting it directly. In their experiment, they boost the tiny shift by a factor of 10,000, detecting it for the first time and characterizing it at the angstrom scale. This realizes one of the long-standing promises of weak measurement and demonstrates its potential in precision measurements.

ScienceFeb 7, 200843 citations

Determination of the focused beam waist of lasers with weak measurements

Linguo Xie, Xiaodong Qiu, Jiangdong Qiu +3 more

In this Letter, a method for detecting the focused beam waist of lasers is proposed by using weak measurements based on the so-called weak-value amplification. We establish a propagation model to describe the quantitative relation between the beam waist and the amplified shift of the spin Hall effect of light (SHEL), which is sensitive to the variation of the beam waist. We experimentally measure the amplified shift corresponding to a different beam waist and the experimental data agrees well with theoretical calculation. These results confirm the rationality and feasibility of our method.

Chinese Optics LettersJan 1, 20159 citations

Estimation of optical rotation of chiral molecules with weak measurements

Xiaodong Qiu, Linguo Xie, Xiong Liu +3 more

From its beginning, the measurement of optical rotation (OR) is crucial for the analysis of chiral molecules in many fields. However, the precision measurement of a weak OR signal with conventional setup remains elusive. In this Letter, we experimentally propose a precision method to determine the OR of glucose and fructose based on weak measurements. By using the spin Hall effect of light (SHEL) as a probe, a nonlinear weak measurements model is established that is applicable beyond the Aharonov-Albert-Vaidman (AAV) limit. Due to the high sensitivity of weak measurements amplification with respect to the OR, a tremendous variation of the amplified beam displacement of the SHEL is observed, while the concentration of glucose and fructose is slightly changed.

Optics LettersAug 23, 2016136 citations