NRPA: Neural Recommendation with Personalized Attention

Existing review-based recommendation methods usually use the same model to learn the representations of all users/items from reviews posted by users towards items. However, different users have different preference and different items have different characteristics. Thus, the same word or similar reviews may have different informativeness for different users and items. In this paper we propose a neural recommendation approach with personalized attention to learn personalized representations of users and items from reviews. We use a review encoder to learn representations of reviews from words, and a user/item encoder to learn representations of users or items from reviews. We propose a personalized attention model, and apply it to both review and user/item encoders to select different important words and reviews for different users/items. Experiments on five datasets validate our approach can effectively improve the performance of neural recommendation.Comment: 4 pages, 4 figure

Non-reciprocal cavity polariton

Breaking the time-reversal symmetry of light is of great importance for fundamental physics, and also have attracted increasing interests in the study of non-reciprocal photonics for applications. The optical non-reciprocity has been realized by engineering the susceptibility of dielectric, through either magneto-optics effect with bias magnetic field or directional coherent nonlinear optical effects stimulated by external drives. Here, we experimentally demonstrate an inherently non-reciprocal quasiparticle, i.e. the cavity polariton, in a strongly coupled cavity quantum electrodynamics system. Through carefully manipulating the internal quantum state of atoms to break the time-reversal symmetry, the polariton shows non-reciprocal photon emission without bias field. Such non-reciprocal polariton state leads to optical isolation exceeds 30dB on single-quanta level ($\sim0.1$ photon), and also produces non-reciprocal non-classical statistics with coherent probe lights, manifesting the quantum nature of the non-reciprocal polaritons. Such new quasiparticle demonstrated in this work holds great potential for exploring the quantum non-reciprocity in photonics and quantum network applications, and also new topological phases in many-body physics.Comment: 6 pages, 4 figure

Superiority of Multi-Head Attention in In-Context Linear Regression

We present a theoretical analysis of the performance of transformer with softmax attention in in-context learning with linear regression tasks. While the existing literature predominantly focuses on the convergence of transformers with single-/multi-head attention, our research centers on comparing their performance. We conduct an exact theoretical analysis to demonstrate that multi-head attention with a substantial embedding dimension performs better than single-head attention. When the number of in-context examples D increases, the prediction loss using single-/multi-head attention is in O(1/D), and the one for multi-head attention has a smaller multiplicative constant. In addition to the simplest data distribution setting, we consider more scenarios, e.g., noisy labels, local examples, correlated features, and prior knowledge. We observe that, in general, multi-head attention is preferred over single-head attention. Our results verify the effectiveness of the design of multi-head attention in the transformer architecture

Secondary Grouting Pressure Limit of Shield Tunnels in Loess Strata Based on Bolt Shear Behavior

A loess stratum was selected as the research object, assuming that the slurry diffuses in a hemispherical shape during secondary grouting. Based on the unified strength theory describing the failure characteristics of loess and the critical condition of bolt shear failure, the critical pressure value of the secondary grouting in loess strata was determined theoretically. The reliability of the theoretical analysis was verified by the numerical modeling realizing the large deformation of formation and the dynamic injection of slurry. The critical grouting pressure of 821.80 kPa of theoretical calculation was obtained. Comparing the results of the numerical simulation analysis, it was found that the critical grouting pressure calculated using the theoretical equation had a safety index of 1.14. Bounded by βu (the ratio of expansion radius RP of soil plastic zone to the expansion radius Ru of the slurry) equal to 2.65, the water pressure at the grouting port is the main factor affecting the upper limit of critical grouting pressure when it is less than 2.65, and the effective internal friction angle of soil layer is the main factor when it is greater than 2.65. The influence of matric suction on the upper limit of the critical grouting pressure can be ignored