The establishment of China's space station, can not do without this high cold "clock"!

产品：格致道教论坛

Product: Gezhi Forum on Taoism

以下是中国科学院上海光学与精密机械研究所副研究员瞿秋志的致辞

The following is a speech by Qu Qiuzhi, associate researcher of Shanghai Institute of Optics and precision machinery, Chinese Academy of Sciences

首先，让我问你一个问题：什么是时间？这个问题听起来很熟悉。我们每个人每天都在看时间，但当有人问你"什么是时间"时，回答起来可能就不那么容易了。

First of all, let me ask you a question: what is time? This question sounds familiar. Everyone of us keeps looking at the time every day, but when someone asks you "what is time", it may not be so easy to answer.

古罗马著名思想家荷马说："如果没有人问我这个问题，我想我知道时间是什么；但如果有人问我，我什么都不知道。"爱因斯坦也说过这个问题。当有人问他时间是什么时，爱因斯坦说："空间和时间只是我们人类思维的方式，而不是我们生存的条件。"

Homer, a famous thinker in ancient Rome, said: "if no one asks me this question, I think I know what time is; But if someone asks me, I don't know anything. " Einstein also said this question. When someone asked him what time is, Einstein said: "space and time are only the mode of our human thinking, not the conditions for our survival."

你看，在古代，我们通过观察太阳、月亮和星星的周期性运动来区分时间。根据他们的位置，我们可以简单地判断时间。我们称这种钟为自然钟。自然时钟没有精确性。它可能能分辨出是早上、下午还是晚上。

You see, in ancient times, we distinguished time by looking at the periodic movements of the sun, the moon and the stars. By their position, we can simply judge the time. We call this kind of clock natural clock. A natural clock has no precision. It can probably tell whether it is morning, afternoon or evening.

如果我们实现了这一愿景，我们可以将目前导航系统的定位精度从10米降低到不足米，甚至可以降低到不足厘米或毫米。那时，无人驾驶和智能汽车可以得到广泛的应用。然而，要把冷原子钟送上天堂是非常困难的。

If we achieve this vision, we can reduce the positioning accuracy of the current navigation system from 10 meters to less than meters, or even to less than centimeters or millimeters. At that time, driverless and intelligent cars could be applied in a large range. However, it is very difficult to send the cold atomic clock to heaven.

我在2000年加入这个团队，开始做激光冷却实验。五年后，我们在中国制造了第一个玻色-爱因斯坦凝聚体。那时，我们的激光冷却技术非常成熟，所以我们开始制造太空冷原子钟。这是一个太空冷原子钟的原型，我们是在一个完全空白的实验室里建造的。

I joined this team in 2000 and began to do laser cooling experiments. Five years later, we made the first Bose Einstein condensate in China. At that time, our laser cooling technology was very mature, so we began to make space cold atomic clocks. This is a prototype of a space cold atomic clock that we built from a completely blank laboratory.

我们最多只能有两台激光器。在正常情况下，我们只能用六个激光器来完成事情。现在我们只用两个激光来完成。没有办法完成它们！但工作必须要做。最后，我们制作了这样一个系统。

We can only have two lasers at most. Under normal circumstances, we can only use six lasers to complete things. Now let's only use two lasers to complete things. There's no way to complete them! But work has to be done. Finally, we made such a system.

这个系统是由两束光的多次反射来完成的，这样就不会浪费一点能量。我们最后制造了一个原子激光笼子，并把原子放进去。这就是我们太空冷原子钟的工作原理。

This system is completed by multiple reflections of two beams of light, so that a little energy will not be wasted. We finally made a laser cage of atoms and put atoms in it. This is the working principle of our space cold atomic clock.

我刚刚用两个词来概括这个钟：一个是高的，另一个是冷的。它是所有冷原子钟中轨道最高的钟；它是所有高轨道原子钟中温度最低的原子钟。我用一种非常机械的语言对全国人民说："我们的太空冷原子钟已经准备好了。"

I have just said two words to summarize this clock: one is high, the other is cold. It is the clock with the highest orbit of all cold atomic clocks; It is the lowest temperature atomic clock in all high orbit atomic clocks. I said to the people all over the country in a very mechanical language, "our space cold atomic clock is all right and ready."

这个钟已经在天空中运行了34个月，它的目标是实现3000万年误差的1秒。最终，它实现了4200万年一秒的误差。它的一些在轨实验发表在《自然通讯》杂志上。结果发表后，得到了许多国际专家的高度评价。

The clock has been in the sky for 34 months, and its target is to achieve 30 million years error of one second. In the end, it achieved 42 million years error of one second. Some of its on orbit experiments were published in the journal Nature communication. After the results were published, we received high praise from many international experts.

Link：https://new.qq.com/omn/20210429/20210429A05H1X00.html

update time：2021-04-29 14:01:48