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Cavity magnomechanics using mechanical degrees of freedom in ferromagnetic crystals provides a powerful platform for observing many interesting classical and quantum nonlinear phenomena in the emerging field of magnon spintronics. However, to date, the generation and control of chaotic motion in a cavity magnomechanical system remain an outstanding challenge due to the inherently weak nonlinear interaction of magnons. Here, we present an efficient mechanism for achieving magnomechanical chaos, in which the magnomechanical system is coherently driven by a two-tone microwave field consisting of a pump field and a probe field. Numerical simulations show that the relative phase of the two input fields plays an important role in controlling the appearance of chaotic motion and, more importantly, the threshold power of chaos is reduced by 6 orders of magnitude from watts to microwatts. In addition to providing insight into magnonics nonlinearity, cavity magnomechanical chaos will always be of interest because of its significance both in fundamental physics and potential applications ranging from ultra-low threshold chaotic motion to chaos-based secret information processing.

This paper presents a video coding scheme that combines traditional optimization methods with deep learning methods based on the Enhanced Compression Model (ECM). In this paper, the traditional optimization methods adaptively adjust the quantization parameter (QP). The key frame QP offset is set according to the video content characteristics, and the coding tree unit (CTU) level QP of all frames is also adjusted according to the spatial-temporal perception information. Block importance mapping technology (BIM) is also introduced, which adjusts the QP according to the block importance. Meanwhile, the deep learning methods propose a convolutional neural network-based loop filter (CNNLF), which is turned on/off based on the rate-distortion optimization at the CTU and frame level. Besides, intra-prediction using neural networks (NN-intra) is proposed to further improve compression quality, where 8 neural networks are used for predicting blocks of different sizes. The experimental results show that compared with ECM-3.0, the proposed traditional methods and adding deep learning methods improve the PSNR by 0.54 dB and 1 dB at 0.05Mbps, respectively; 0.38 dB and 0.71dB at 0.5 Mbps, respectively, which proves the superiority of our method.

Magnonic frequency combs have recently attracted particular attention due to their potential impact on spin-wave science. Here, we demonstrate theoretically the generation of ultra-wideband (UWB) magnonic frequency combs induced by dissipative coupling in an open cavity magnomechanical system. A broadband comb with gigahertz repetition rates is obtained in the magnonic spectrum and a typical non-perturbation frequency-comb structure is also observed. The total width of the magnonic comb in the robust plateau region can be up to 400 comb lines, which is much broader and flatter than the reported in the previous works. Furthermore, when the dissipative coupling strength is further increased, the chaotic motion is predicted in the magnonic spectrum. Our results provide an in-depth understanding of nonlinear magnomechanic dynamics in open quantum systems and fundamentally broadens the research range of magnon in new spectral regimes., Comment: 5

This paper investigates the downlink channel state information (CSI) sensing in 5G heterogeneous networks composed of user equipments (UEs) with different feedback capabilities. We aim to enhance the CSI accuracy of UEs only affording the low-resolution Type-I codebook. While existing works have demonstrated that the task can be accomplished by solving a phase retrieval (PR) formulation based on the feedback of precoding matrix indicator (PMI) and channel quality indicator (CQI), they need many feedback rounds. In this paper, we propose a novel CSI sensing scheme that can significantly reduce the feedback overhead. Our scheme involves a novel parameter dimension reduction design by exploiting the spatial consistency of wireless channels among nearby UEs, and a constrained PR (CPR) formulation that characterizes the feasible region of CSI by the PMI information. To address the computational challenge due to the non-convexity and the large number of constraints of CPR, we develop a two-stage algorithm that firstly identifies and removes inactive constraints, followed by a fast first-order algorithm. The study is further extended to multi-carrier systems. Extensive tests over DeepMIMO and QuaDriGa datasets showcase that our designs greatly outperform existing methods and achieve the high-resolution Type-II codebook performance with a few rounds of feedback., Comment: This work has been submitted to the IEEE for possible publication

An analogous laser action of magnons would be a subject of interest and is crucial for the study of nonlinear magnons spintronics. Here, we demonstrate the magnon laser behavior based on Brillouin light scattering in a ferrimagnetic insulator sphere which supports optical whispering gallery modes and magnon resonances. We show that the excited magnon plays what has traditionally been the role of the Stokes wave and is coherently amplified during the Brillouin scattering process, making magnon laser possible. Furthermore, the stimulating excited magnon number increasing exponentially with the input light power can be manipulated by adjusting the external magnetic field. In addition to providing insight into magneto-optical interaction, the study of magnon laser action will help to develop novel technologies for handling spin-wave excitations and could affect scientific fields beyond magnonics. Potential applications range from preparing coherent magnon sources to operating onchip functional magnetic devices.

The implementation of a single magnon level quantum manipulation is one of the fundamental targets in quantum magnetism with a significant practical relevance for precision metrology, quantum information processing, and quantum simulation. Here, we demonstrate theoretically the feasibility of using a hybrid ferromagnet-superconductor quantum system to prepare a single magnon source based on magnon blockade effects. By numerically solving the quantum master equation, we show that the second-order correlation function of the magnon mode depends crucially on the relation between the qubit-magnon coupling strength and the driving detuning, and simultaneously signatures of the magnon blockade appear only under quite stringent conditions of a cryogenic temperature. In addition to providing perception into the quantum phenomena of magnon, the study of magnon blockade effects will help to develop novel technologies for exploring the undiscovered magnon traits at the quantum level and may find applications in designing single magnon emitters.

Magnon as a quantized spin wave has attracted extensive attentions in various fields of physics, such as magnon spintronics, microwave photonics, and cavity quantum electrodynamics. Here, we explore theoretically magnon chaos-order transition in cavity optomagnonics, which is still remains largely unexplored in this emerging field. We find that the evolution of the magnon experiences the transition from order to period-doubling bifurcation and finally enter chaos by adjusting the microwave driving power. Different from the normal chaos, the magnon chaos-order transition proposed here is phase-mediated. Beyond their fundamental scientific significance, our results will contribute to the comprehending of nonlinear phenomena and chaos in optomagnonical system, and may find applications in chaos-based secure communication.

Magnon Kerr nonlinearity plays crucial roles in the study of cavity optomagnonics system and may bring many novel physical phenomena and important applications. In this work, we report the investigation of high- order sideband generation induced by magnon Kerr nonlinearity in a cavity-magnon system, which is critically lacking in this emerging research field. We uncover that the driving field plays a significant role in controlling the generation and amplification of the higher-order sidebands and the sideband spacing can be adjusted by regulating the beat frequency between the pump laser and the probe laser, which is extremely eventful for the spacing modulation of the sideband spectrum. Based on the recent experimental progress, our results deepen our cognition into optomagnonics nonlinearity and may find interesting applications in optical frequency metrology and optical communications., Comment: 5 pages, 4 figures

It is quite important to enhance and control the optomechanically induced high-order sideband generation to achieve low-power optical comb and high-sensitivity sensing with an integratable structure. Here we present and analyze a proposal for enhancement and manipulation of optical nonlinearity and high-order sideband generation in a hybrid atom-cavity optomechanical system that is coherently driven by a bichromatic input field consisting of a control field and a probe field and works beyond the perturbative regime. Our numerical analysis with experimentally achievable parameters confirms that robust high-order sideband generation and typical spectral structures with non-perturbative features can be created even under weak driven fields. The dependence of the high-order sideband generation on the atomic parameters are also discussed in detail, including the decay rate of the atoms and the coupling parameter between the atoms and the cavity field. We show that the cutoff order as well as the amplitude of the higher order sidebands can be well tuned by the atomic coupling strength and the atomic decay rate. The proposed mechanism of enhancing optical nonlinearity is quite general and can be adopted to optomechanical systems with different types of cavity.

Difference-sideband generation in an optomechanical system coupled to a charged object is investigated beyond the conventional linearized description of optomechanical interactions. An exponential decay law for difference-sideband generation in the presence of electric interaction is identified which exhibits more sensitivity to electrical charges than the conventional linearized effects. Using exact the same parameters with previous work based on the linearized dynamics of the optomechanical interactions, we show that optomechanically induced difference-sideband generation may enable an all-optical sensor for precision measurement of electrical charges with higher precision and lower power. The proposed mechanism is especially suited for on-chip optomechanical devices, where nonlinear optomechanical interaction in the weak coupling regime is within current experimental reach.

Relational probabilistic models have the challenge of aggregation, where one variable depends on a population of other variables. Consider the problem of predicting gender from movie ratings; this is challenging because the number of movies per user and users per movie can vary greatly. Surprisingly, aggregation is not well understood. In this paper, we show that existing relational models (implicitly or explicitly) either use simple numerical aggregators that lose great amounts of information, or correspond to naive Bayes, logistic regression, or noisy-OR that suffer from overconfidence. We propose new simple aggregators and simple modifications of existing models that empirically outperform the existing ones. The intuition we provide on different (existing or new) models and their shortcomings plus our empirical findings promise to form the foundation for future representations., Comment: 8 pages, Accepted at Statistical Relational AI (StarAI) workshop 2017