2021年经济学人 间谍活动--中科大再造"穿墙术"(2)

Mirror, mirror, you're the wall

镜子，镜子，你就是那面墙

Dr Xu and Dr Pan conducted their trial at night, to minimise the amount of background light that might have interfered¹ with the results. Their targets, a dummy² of a human being on one experimental run and a giant "H" on another, were concealed³ behind a barrier in an apartment in a block of flats in Shanghai. Their laser and receiving apparatus⁴ were in a second apartment block 1.43km away. The receiving apparatus, an instrument called a single-photon avalanche⁵ diode (spad), was, as its name suggests, so sensitive that it could detect and count individual photons, the particles of which light beams are composed. This was just as well, for, of every seven million billion photons fired across the gap by the laser, only a single one returned.

徐飞虎和潘建伟在夜间试验为的是将可能干扰试验结果的背景光降至最弱。他们在一次实验中试图看到的目标是个假人，在另一次实验中是一个巨大的字母H，它们都被隐藏在上海一幢公寓楼中某间房屋里的障碍物后面。他们的激光及接收设备位于1.43公里外的第二栋公寓楼内。接收设备是一台叫作单光子雪崩二极管（SPAD）的仪器，听名字就足以知道它的灵敏度非常高，可以探测和计数单个光子，即组成光束的粒子。这再好不过了，因为在他们的激光射出的每七千万亿个光子中，只有一个光子返回。

Because each firing of the laser yielded so little information, the researchers had to take many shots to build up an image. To that end, they imagined a grid⁶ on the target wall, 64 dots wide and 64 deep. They fired the laser at each dot in turn, and then fed the data from the spad into an algorithm capable of reconstructing, albeit⁷ fuzzily, an image of the hidden object.

由于每次激光发射得出的信息太少，研究人员不得不进行大量拍摄以建构一幅图像。为此，他们在目标墙上想象出一个64个点宽、64个点深的网格。他们依次向每个点发射激光，然后把来自SPAD的数据输入能够重建隐藏物体（尽管是模糊的）影像的算法。

The military applications of this technology suggest themselves. They were, after all, why Dstl sponsored Dr Faccio in the first place. But others are also interested. America's space agency, nasa, has paid for such work in the past in the hope of putting a laser on a satellite orbiting a distant world. This would permit the photographing of the otherwise-invisible interiors of caverns⁸ on the surfaces of moons and planets. And, in a more practical vein⁹, engineers in the autonomous-vehicle industry would be keen on a technology that let their cars spot other motorists blithely¹⁰ speeding around blind corners.

这项技术在军事上的应用不言而喻，毕竟这正是Dstl当初资助法乔做这个项目的原因。不过还有其他感兴趣的人群。美国国家航空航天局（NASA）在过去就曾为这类研究买单，希望能把激光安装在绕遥远天体运行的卫星上，这样就可以拍摄到卫星和行星表面那些原本不可见的洞穴内部。而且，更实用的是，无人驾驶汽车行业的工程师会热衷于这种技术，因为这能让他们的汽车“看到”在盲区弯道飞驰的其他车辆。

For now, such applications remain far in the future. Capturing the experimental data in Shanghai took several hours, which is of little use either on the road or in fastmoving situations like hostage-taking. The amount of light lost between bounces also puts a limit on how far away an object can be from the reflecting wall before the technique stops being useful. The dummy used by Dr Xu and Dr Pan was 75cm from the wall, which is probably near that limit. These caveats¹¹ aside, however, performing the trick over a distance of almost 1+1/2km is a staggering advance on previous efforts. It would not be surprising, says Dr Faccio, now that it is known what is possible, if that record, too, were broken.

目前这类应用仍遥不可及。在上海捕捉的实验数据耗时达几个小时，这要放到道路上或是像劫持人质这样快速变动的场景下并没有什么用处。来回反射间损失的光量也限制了这项技术要起作用物体可以距离反射墙面多远。徐飞虎和潘建伟使用的假人离墙75厘米，可能已经接近极限。然而，撇开这些限制不谈，在近1.5公里的距离上演这个戏法，相比之前的成果可谓进步惊人。法乔说，既然现在已经知道了什么是可能的，那么哪天这项记录也被打破就不足为奇了。

1 interfered   

v.干预( interfere的过去式和过去分词 )；调停；妨碍；干涉

参考例句：

• Complete absorption in sports interfered with his studies. 专注于运动妨碍了他的学业。 来自《简明英汉词典》
• I am not going to be interfered with. 我不想别人干扰我的事情。 来自《简明英汉词典》

2 dummy   

n.假的东西；(哄婴儿的)橡皮奶头

参考例句：

• The police suspect that the device is not a real bomb but a dummy.警方怀疑那个装置不是真炸弹，只是一个假货。
• The boys played soldier with dummy swords made of wood.男孩们用木头做的假木剑玩打仗游戏。

3 concealed   

a.隐藏的，隐蔽的

参考例句：

• The paintings were concealed beneath a thick layer of plaster. 那些画被隐藏在厚厚的灰泥层下面。
• I think he had a gun concealed about his person. 我认为他当时身上藏有一支枪。

4 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

5 avalanche   

n.雪崩，大量涌来

参考例句：

• They were killed by an avalanche in the Swiss Alps.他们在瑞士阿尔卑斯山的一次雪崩中罹难。
• Higher still the snow was ready to avalanche.在更高处积雪随时都会崩塌。

6 grid   

n.高压输电线路网；地图坐标方格；格栅

参考例句：

• In this application,the carrier is used to encapsulate the grid.在这种情况下，要用载体把格栅密封起来。
• Modern gauges consist of metal foil in the form of a grid.现代应变仪则由网格形式的金属片组成。

7 albeit   

conj.即使；纵使；虽然

参考例句：

• Albeit fictional,she seemed to have resolved the problem.虽然是虚构的，但是在她看来好象是解决了问题。
• Albeit he has failed twice,he is not discouraged.虽然失败了两次，但他并没有气馁。

8 caverns   

大山洞，大洞穴( cavern的名词复数 )

参考例句：

• Within were dark caverns; what was inside them, no one could see. 里面是一个黑洞，这里面有什么东西，谁也望不见。 来自汉英文学 - 家（1-26） - 家（1-26）
• UNDERGROUND Under water grottos, caverns Filled with apes That eat figs. 在水帘洞里，挤满了猿争吃无花果。

9 vein   

n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络

参考例句：

• The girl is not in the vein for singing today.那女孩今天没有心情唱歌。
• The doctor injects glucose into the patient's vein.医生把葡萄糖注射入病人的静脉。

10 blithely   

adv.欢乐地，快活地，无挂虑地

参考例句：

• They blithely carried on chatting, ignoring the customers who were waiting to be served. 他们继续开心地聊天，将等着购物的顾客们置于一边。 来自《简明英汉词典》
• He blithely ignored her protests and went on talking as if all were agreed between them. 对她的抗议他毫不在意地拋诸脑后，只管继续往下说，仿彿他们之间什么都谈妥了似的。 来自《简明英汉词典》

11 caveats   

警告

参考例句：

• I would offer a caveat for those who want to join me in the dual calling. 为防止发生误解，我想对那些想要步我后尘的人提出警告。 来自辞典例句
• As I have written before, that's quite a caveat. 正如我以前所写，那确实是个警告。 来自互联网