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Exploring high sensitivity on the measurement of angular rotations is an outstanding challenge in optics and metrology. In this work, we employ the mn-order Hermite-Gaussian 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 2mn+m+n. For verification, we perform an optical experiment where the minimum detectable angular rotation improves $\sqrt{15}$-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., Comment: 21 pages, 8 figures, 3 tables. Published in Photonics Research

The weak-value amplification technique has been proved to be useful for precision metrology in both theory and experiment. To explore the ultimate performance of weak-value amplification for multiparameter estimation, we investigate a general weak-measurement formalism with the assistance of the high-order Hermite-Gaussian (H-G) pointer and the quantum Fisher information matrix. Theoretical analysis shows that the ultimate precision of our scheme is improved by a factor of the square root of $2n+1$, where $n$ is the order of the Hermite-Gaussian mode. Moreover, the parameters' estimation precision can approach the precision limit with the maximum-likelihood estimation method and the homodyne method. We also present a proof-of-principle experimental setup to validate the H-G--pointer theory and explore its potential applications in precision metrology.

High precision phase estimation is at the core of modern physics and practical applications. We investigate a method for high precision phase estimation via inserting a reference state which enables weak measurement technique to be used in wide dynamic range. A reference phase is introduced artificially to offset the time delay between preselection state and reference state. The sensitivity of measured phase and the linear dynamic range are controllable by adjusting reference phase. Moreover, an arbitrary postselection in measurement is applicable by choosing appropriate reference phase. This method has merits of controllable sensitivity and wide dynamic range, which shows great potential practical applications in high precision phase measurement.

High-precision temperature measurement with adjustable operating range is investigated and experimentally demonstrated based on weak measurement in the frequency domain. The operating range of measurement is precisely modulated by introducing a dynamic extra time delay to the post-selection pumped by a femtosecond laser. By choosing appropriate nonlinear materials and the attenuation, the resolution of the optimized extra time delay can be improved by two orders of magnitude over that of a traditional phase delay compensator. Considering the influence of noise in the experiment, the highest precision of 8.03 × 10−7 °C can be achieved by using a currently available spectrometer. Moreover, the average sensitivity can reach to 38 nm/°C. Taking advantage of the high precision and adjustable operating range, the proposed method has great potential applications in high-precision temperature measurements.

Hamiltonian estimation is a cardinal task in applications of quantum metrology, quantum computation, quantum simulation, etc. When the evolution time is short in order to suppress noise and enhance sensitivity, the measurement and postprocessing may incur high cost. In this paper, we propose an adaptive weak measurement scheme for Hamiltonian estimation, which adjusts the pre- and post-selection according to the difference of the mean shift between two orthogonal post-selected states. According to the angle of the post-selected state, the proposed scheme can change from weak value amplification (WVA) to joint weak measurement (JWM). A study of the quantum Fisher information shows that the JWM situation is always optimal. Meanwhile, the WVA approach loses a little information but it can inherit the WVA’s technical advantages, which are suitable for short evolution times. The widely applicable scope of the proposed scheme makes us believe that it offers a new path for the understanding of unknown Hamiltonians.