Invisibility Cloak One Step Closer to Reality
Look out, Harry Potter: researchers have advanced the study of cloaking—rendering objects invisible by forcing light waves to act as if the objects weren't there.
In a paper published in this week's Science, a team from Duke University and Southeast University in Nanjing, China, reports a new and improved cloak that can conceal a bump—and anything hidden beneath—on a flat surface. Both the surface and the bump must be reflective, however. The new setup is upgraded to function for a relatively broad spectrum of light, whereas previous models had very narrow operational regimes.
This cloak, like its predecessors from the group of David Smith, an electrical and computer engineering professor at Duke, is built from metamaterials—novel composite structures designed to make light work in unusual ways.
Although the new cloak represents a step forward, even this "broadband" model is still a long way from rerouting visible light. The wavelengths of the microwave radiation regime in which the cloak works are tens of thousands of times longer than those of visible light.
隐身衣离现实越来越近
哈利·波特，请注意：研究者们在隐身衣（隐身衣通过对光波的作用，使得物体看起好像来并不存在）方面的研究又有了进展。
来自杜克大学和中国南京的东南大学的一个研究团队在本周《科学》杂志上（Science）发表的一篇文章中报道了他们制造的一种新型而且效果更好的隐身衣，这种隐身衣能隐藏平面上的突起——以及任何隐藏在突起下面的物质。但是，平面和突起必须是可反射的。新的设计可以使隐身衣在相对更宽的光谱范围内使用，但是以前的隐身衣的可操作性光谱范围非常狭窄。
杜克大学的电子与计算机工程教授大卫·史密斯（David Smith）的研究小组以前设计过一种隐身衣，而这款新的隐身衣和大卫·史密斯设计的隐身衣一样是由“超材料”制备而来的，“超材料”是一种新型的复合材料，它能使光具有不同寻常的性质。
虽然这种新的隐身衣代表了一种进步，但是即使是这样的“宽带”模式，它要达到隐藏可见光的目的，仍然还有很远的距离要走。这种隐身衣的工作范围属于微波辐射，其波长比是可见光波长的数万倍。
Vocabulary:
Invisibility：不可见
Cloak：大氅；斗篷
Render：使…变为
Conceal：隐藏
Bump: 突起；肿块
Reflective: 反射的
Operational: 可操作的
Reroute: 绕行；改线
Metamaterial: 超材料（也翻译为亚材料，一种人工材料，具有自然物质所不具备的一些特殊性质，比如负折射率）
Microwave Radiation: 微波辐射
（英语原文来自SCIENTIFIC AMERICAN《科学美国人》
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