Apple Watch,苹果公司在去年9月苹果秋季新品发布会上以＂犹抱琵琶半遮面＂般的形式证实了它的存在。在随后的数月里,消费者和媒体都试图掀开苹果这款传说已久的智能设备的面纱。无论是主流科技网站还是数码产品论坛,都无不充斥着各种关...Apple Watch,苹果公司在去年9月苹果秋季新品发布会上以＂犹抱琵琶半遮面＂般的形式证实了它的存在。在随后的数月里,消费者和媒体都试图掀开苹果这款传说已久的智能设备的面纱。无论是主流科技网站还是数码产品论坛,都无不充斥着各种关于Apple Watch真实面目的猜测。最终,这场众说纷纭的猜谜游戏在今年彻底被苹果公司画上了句号。展开更多
MP3播放器体积小巧，MP3格式音乐来源非常自由，所以MP3早已成为最普及的音乐随身听。对于音频功能的发展，MP3可供提高的空间已经非常有限了。厂家为了打开大家欲望的缺口，开始打起大家眼睛的主意。想法催生行动，很快能播放视频文件...MP3播放器体积小巧，MP3格式音乐来源非常自由，所以MP3早已成为最普及的音乐随身听。对于音频功能的发展，MP3可供提高的空间已经非常有限了。厂家为了打开大家欲望的缺口，开始打起大家眼睛的主意。想法催生行动，很快能播放视频文件的MP4播放器应运而生了。 MP4播放器是一个能够播放MPEG-4文件的设备，它可以叫做PVP(Personal Video Player，个人视频播放器)也可以叫做PMP(Portable Media Player。展开更多
We study a simplified version of the Sachdev-Ye-Kitaev(SYK) model with real interactions by exact diagonalization. Instead of satisfying a continuous Gaussian distribution, the interaction strengths are assumed to be ...We study a simplified version of the Sachdev-Ye-Kitaev(SYK) model with real interactions by exact diagonalization. Instead of satisfying a continuous Gaussian distribution, the interaction strengths are assumed to be chosen from discrete values with a finite separation. A quantum phase transition from a chaotic state to an integrable state is observed by increasing the discrete separation. Below the critical value, the discrete model can well reproduce various physical quantities of the original SYK model,including the volume law of the ground-state entanglement, level distribution, thermodynamic entropy,and out-of-time-order correlation(OTOC) functions. For systems of size up to N=20, we find that the transition point increases with system size, indicating that a relatively weak randomness of interaction can stabilize the chaotic phase. Our findings significantly relax the stringent conditions for the realization of SYK model, and can reduce the complexity of various experimental proposals down to realistic ranges.展开更多
文摘MP3播放器体积小巧，MP3格式音乐来源非常自由，所以MP3早已成为最普及的音乐随身听。对于音频功能的发展，MP3可供提高的空间已经非常有限了。厂家为了打开大家欲望的缺口，开始打起大家眼睛的主意。想法催生行动，很快能播放视频文件的MP4播放器应运而生了。 MP4播放器是一个能够播放MPEG-4文件的设备，它可以叫做PVP(Personal Video Player，个人视频播放器)也可以叫做PMP(Portable Media Player。
基金This work was supported by the National Natural Science Foundation of China(11434011,11522436,11774425,11704029)the National Key R&D Program of China(2018YFA0306501)+1 种基金the Beijing Natural Science Foundation(Z180013)the Research Funds of Renmin University of China(16XNLQ03 and 18XNLQ15)。
文摘We study a simplified version of the Sachdev-Ye-Kitaev(SYK) model with real interactions by exact diagonalization. Instead of satisfying a continuous Gaussian distribution, the interaction strengths are assumed to be chosen from discrete values with a finite separation. A quantum phase transition from a chaotic state to an integrable state is observed by increasing the discrete separation. Below the critical value, the discrete model can well reproduce various physical quantities of the original SYK model,including the volume law of the ground-state entanglement, level distribution, thermodynamic entropy,and out-of-time-order correlation(OTOC) functions. For systems of size up to N=20, we find that the transition point increases with system size, indicating that a relatively weak randomness of interaction can stabilize the chaotic phase. Our findings significantly relax the stringent conditions for the realization of SYK model, and can reduce the complexity of various experimental proposals down to realistic ranges.
