Nontrivial evolution and geometric phase for an orbital angular momentum qutrit.

Photonic orbital angular momentum (OAM) offers a promising platform for high-dimensional quantum information processing. While geometric phase (GP) is the crucial tool in enabling intrinsically fault-tolerant quantum computation, the measurement of GP using linear optics remains relatively unexplored in the OAM state space. Here, we propose an experimental scheme to detect GP shifts resulting from the cyclic evolution of OAM qutrit states. Distinguished with the conventional evolution along cyclic path on the Poincaré sphere (PS), the nontrivial evolution in our theoretical scheme is along a cyclic path residing within the SU(3)/U(2) parameter space. By employing a combination of X-gates, dove prisms, and double cylindrical lenses, we achieve the cyclic evolution and analyse the resultant GP through our designed Sagnac interferometer. Our theoretical study may find potential in high-dimensional quantum computation using twisted photons and in exploring the geometric structure of such optical systems.

Geometric interpretation and experimental test of Leggett inequalities with nonmaximally entangled states.

Leggett inequality states that nonlocal hidden-variable models might still be incompatible with the predictions of quantum physics. However, its theoretical and experimental demonstration is only in the scenario of 2-dimensional maximally entangled systems. An open question remains as to whether the Leggett inequality can be violated by nonmaximally entangled states. Here, we answer this question both in theory and experiment. Specifically, from the point of view of geometry, we theoretically map the problem of maximizing the correlation measure in the Leggett inequality to maximizing the sum of an ellipse's diameter and semi-diameter axes, accordingly, demonstrating that the violation of the Leggett inequality requires a more robust entanglement than that of Bell's theory. Experimentally, by leveraging the controllable photonic orbital angular momentum entanglement, we demonstrate the violation of Leggett-type inequalities by more than 8.7 and 4.5 standard deviations under concurrence C = 0.95 and 0.9, respectively. Our observations indicate that, the requirement for quantum correlation should be increased to exclude a particular class of non-local hidden variable theories that abide by Leggett's model, providing insights into the boundaries of quantum correlation and the limitations imposed by non-local hidden variables.

Defect Severity Identification for a Catenary System Based on Deep Semantic Learning.

A variety of Chinese textual operational text data has been recorded during the operation and maintenance of the high-speed railway catenary system. Such defect text records can facilitate defect detection and defect severity analysis if mined efficiently and accurately. Therefore, in this context, this paper focuses on a specific problem in defect text mining, which is to efficiently extract defect-relevant information from catenary defect text records and automatically identify catenary defect severity. The specific task is transformed into a machine learning problem for defect text classification. First, we summarize the characteristics of catenary defect texts and construct a text dataset. Second, we use BERT to learn defect texts and generate word embedding vectors with contextual features, fed into the classification model. Third, we developed a deep text categorization network (DTCN) to distinguish the catenary defect level, considering the contextualized semantic features. Finally, the effectiveness of our proposed method (BERT-DTCN) is validated using a catenary defect textual dataset collected from 2016 to 2018 in the China Railway Administration in Chengdu, Lanzhou, and Hengshui. Moreover, BERT-DTCN outperforms several competitive methods in terms of accuracy, precision, recall, and F1-score value.

Radial diffraction of light in the radial momentum state space.

While linear or angular position and momentum can be linked by a continuous or discrete Fourier transform, there are some subtle problems in the analogous Fourier relationship between radial position and radial momentum in history. Here we exploit radial position and newly introduced radial momentum variables to report a radial version of light's diffraction. The mask with single or multiple radial slits confines the light to a radial transmission function. As a result, in the radial momentum state space, we can observe the diffraction sidebands generated on the transmitted light due to a transverse restriction of the radial range. Our experimental results clearly reveal the intriguing diffraction behaviors between radial position and radial momentum variables at the single-photon level, making them another candidate for fundamental tests of quantum mechanics and for a variety of quantum information applications.

Structured-Pump-Enabled Quantum Pattern Recognition.

We report a new scheme of ghost imaging by using a spatially structured pump in the Fourier domain of spontaneous parametric down-conversion for quantum-correlation-based pattern recognition. We exploit the mathematical feature of Laguerre-Gaussian mode's Fourier transform to describe the pump-modulated formation of a ghost image. Of particular interest is the experimental demonstration of a quantum equivalence of a Vander Lugt filter, based on which the nonlocal spiral phase contrast for vortex mapping and quantum-correlation-based human face recognition are implemented successfully. The photons used for probing a test object, scanning the database, and producing a correlation signal can belong to three different light beams, which suggests some security applications where low-light-level illumination and covert operation are desired.

Realization of the Einstein-Podolsky-Rosen Paradox Using Radial Position and Radial Momentum Variables.

As is well known, angular position and orbital angular momentum (OAM) of photons are a conjugate pair of variables that have been extensively explored for quantum information science and technology. In contrast, the radial degrees of freedom remain relatively unexplored. Here we exploit the radial variables, i.e., radial position and radial momentum, to demonstrate Einstein-Podolsky-Rosen correlations between down-converted photons. In our experiment, we prepare various annular apertures to define the radial positions and use eigenmode projection to measure the radial momenta. The resulting correlations are found to violate the Heisenberg-like uncertainty principle for independent particles, thus manifesting the entangled feature in the radial structure of two-photon wave functions. Our work suggests that, in parallel with angular position and OAM, the radial position and radial momentum can offer a new platform for a fundamental test of quantum mechanics and for novel application of quantum information.

Involvement of ethylene and hydrogen peroxide in induction of alternative respiratory pathway in salt-treated Arabidopsis calluses.

The role of ethylene and hydrogen peroxide (H2O2) in the induction of the alternative respiratory pathway (AP) in calluses from wild-type (WT) Arabidopsis and ethylene-insensitive mutant etr1-3 under salt stress was investigated. The capacity and the contribution of the AP to the total respiration were significantly induced by 100 mM sodium chloride (NaCl) in WT calluses but only slightly induced in etr1-3 calluses. Ethylene emission was enhanced in WT calluses under salt stress. Application of 1-aminocyclopropane-1-carboxylic acid (an ethylene precursor) further increased the AP capacity in WT calluses but not in etr1-3 calluses under salt stress. Reduction of ethylene production by aminooxyacetic acid (AOA, an ethylene biosynthesis inhibitor) in WT calluses eliminated the NaCl-induced increase of ethylene emission and inhibited AP induction under salt stress, suggesting that ethylene is required for AP induction. H2O2 enhanced ethylene production while ethylene reduced H2O2 generation in WT calluses under salt stress. In addition, ethylene and H2O2 modulated NaCl-induced alternative oxidase gene (AOX1a) expression and the increase in pyruvate content in WT calluses. Inhibition of the AP by salicylhydroxamic acid in WT calluses under salt stress resulted in severe cellular damage as indicated by the high content of H2O2, malondialdehyde and more electrolyte leakage. Taken together, ethylene and H2O2 are involved in the salt-induced increase of the AP, which plays an important role in salt tolerance in WT calluses, and ethylene may be acting downstream of H2O2.