利用手机的一组小实验

手机用于教学别具新意,令人耳目一新,使人感到物理就在身边.下面就为大家提供几则实例.     

领导者的必备素质：妥协与宽容

我们常常说,一个领导人的重要素质是方向、节奏.他的水平就是合适的灰度. 1944年出生于贵州省都匀,祖籍浙江省.肄业于重庆建筑工程学院(现并入重庆大学),中学毕业后在重庆建筑工程学院暖通专业学习,毕业后参军从事军事科技研发.后创立华为技术有限公司,现为华为技术有限公司总裁.     

让人耳不暇接的视听盛宴——走进2009年白云音响展

步入金秋时节，在音响业界又迎来了一年一度的视听盛宴，它就是在广州白云会展中心举行A92009年度白云音响大展。本次音响展延续在香港刚刚落幕的视听展余音，各路音响厂商纷纷亮出了看家音响器材，为到场的发烧友奉献了一场场耳不暇接、异彩纷呈的音响视听盛宴。     

Spectral feature with sub-natural linewidth due to quantum interference in a four-level system

This paper studies the narrow spectral feature appearing in a four-level system coupled by two strong coherent fields and probed by a weak laser field. The linewidth is examined as a function of the Rabi frequencies of coupling fields, and the result is explained by using the dressed-state formalism.     

Scheme for implementing quantum dense coding with four-particle decoherence-free states in an ion trap

This paper proposes an experimentally feasible scheme for implementing quantum dense coding of trapped-ion system in decoherence-free states. As the phase changes due to time evolution of components with different eigenenergies of quantum superposition are completely frozen, quantum dense coding based on this model would be perfect. The scheme is insensitive to heating of vibrational mode and Bell states can be exactly distinguished via detecting the ionic state.     

Scheme for teleportation of unknown states of trapped ion

A scheme is presented for teleporting an unknown state in a trapped ion system. The scheme only requires a single laser beam. It allows the trap to be in any state with a few phonons, e.g. a thermal motion. Furthermore, it works in the regime, where the Rabi frequency of the laser is on the order of the trap frequency. Thus, the teleportation speed is greatly increased, which is important for decreasing the decoherence effect. This idea can also be used to teleport an unknown ionic entangled state.     

Spin-dependent quantum transport through an Aharonov--Bohm structure spin splitter

Using the tight-binding model approximation, this paper investigates theoretically spin-dependent quantum transport through an Aharonov-Bohm （AB） interferometer. An external magnetic field is applied to produce the spinpolarization and spin current. The AB interferometer, acting as a spin splitter, separates the opposite spin polarization current. By adjusting the energy and the direction of the magnetic field, large spin-polarized current can be obtained.     

Fabrication of high-quality submicron Nb/Al--AlOx/Nb tunnel junctions

Nb/Al-AlOx/Nb tunnel junctions are often used in the studies of macroscopic quantum phenomena and superconducting qubit applications of the Josephson devices. In this work, we describe a convenient and reliable process using electron beam lithography for the fabrication of high-quality, submicron-sized Nb/Al-AlOx/Nb Josephson junctions. The technique follows the well-known selective Nb etching process and produces high-quality junctions with Vm=100 mV at 2.3 K for the typical critical current density of 2.2 kA/cm^2, which can be adjusted by controlling the oxygen pressure and oxidation time during the formation of the tunnelling barrier. We present the results of the temperature dependence of the sub-gap current and in-plane magnetic-field dependence of the critical current, and compare them with the theoretical predictions.     

高速铣削过程铣削力建模及析因试验分析

相对于常规切削，高速铣削时切削力的变化更为复杂，研究高速铣削过程中切削力的变化有助于优化切削参数，对实际生产有着重要的指导意义。     

移动WiMAX与3G的博弈

WiMAX技术是目前国际上影响力最大的宽带无线接入技术，该技术基于IEEES02．16空中接口。IEEES02．16工作组与WiMAX论坛之间有着非常紧密的联系与合作，但两者的工作范围和组织形式不同。IEEE802．16工作组是802．16宽带无线接人空中接口标准的制定者，主要针对Wireless MAN的物理层和MAC层制定规范和标准。为了不同厂商产品的互通和形成一个可运营的网络，必然还需要其它支撑技术，所以WiMAX论坛应运而生。WiMAX论坛现已发展有350多个成员单位，其中包括众多业界领先的设备制造商、部件供应商（芯片、射频、天线、软件和测试服务等）、服务供应商和系统集成商。