Distributed caesium frequency standard

这项提议打算在拉瓦尔大学的光学和光子学大楼安装铯频率标准。在国际单位制中，时间是用铯原子能级之间的跃迁来定义的。因此，铯标准可以被视为一个原子钟，在每秒1000万次振荡的电信号上传递秒的定义。该信号可被分发到多个实验室，并可用于同步仪器和测量。这对于精确的时间和频率测量非常重要，这一领域被称为频率计量学。 守时很重要，因为大多数测量单位都与时间直接相关，因为这是我们人类可以最精确地测量的物理量。当你为你的汽车购买了一定数量的汽油，或者当你支付水电费时，你就依赖于国际时间标准。精确时间标准的明显应用包括使用类似GPS的系统进行地理定位，以及在全球范围内同步金融交易。 频率计量正以快速的步伐向光信号转移，因为更高的频率更容易准确测量。光学频率计量与频率梳紧密相连，频率梳是一种特殊类型的激光器，可以发射稳定和重复的短脉冲，可用于将电频率(如原子钟提供的频率)与光学频率联系起来。因此，通过将它们与铯信号进行比较，梳子允许以绝对方式测量光学频率。因此，一个致力于光学计量和开发短脉冲激光器的世界级光学和光子学实验室绝对需要一个最先进的频率标准。 频率梳是精确的光源，除了计量学外，它还有望在几个领域带来革命。第一个也是最重要的可能是光学光谱学，这是一门通过测量不同波长的光与物质的相互作用来确定气体、液体和固体的化学成分的科学。当你喝牛奶时，它的纯度已经用分光计进行了评估，当你查看天气预报来计划一个长周末时，你实际上是在利用卫星上的几个分光计。 原子钟在电信中也很重要，可以将数据信号同步到最高电平。因此，铯标准被安装在电信中心局，以确保所有比特在正确的时间进入互联网频道。因此，在更快、更好、更高效的通信系统中工作的研究人员也需要尽可能好的时钟来同步他们的信号，这是很自然的。 由8名教职员工和30多名研究生组成的研究小组直接短暂地使用了原子钟。此外，铯标准提供的服务还将提供给20多名教授和300名学生。

This proposal intends to install a caesium frequency standard in the optics and photonics building at Université Laval. Time, in the international system of units, is defined using the transition between energy levels of caesium atoms. A caesium standard can thus be seen as an atomic clock delivering the definition of the second on an electrical signal oscillating 10 million times per second. This signal can be distributed to several laboratories and can be used to synchronize instrumentation and measurements. This is important for precise time and frequency measurements, a field called frequency metrology. Time keeping is important because most measurement units are directly linked to time, as this is the physical quantity that we humans can measure most precisely. When you buy a volume of gas for your car or when you pay your utility bill, you rely on the international time standard. Obvious applications of a precise time standard include geo-localization using GPS-like systems and synchronizing financial transactions on a global scale. Frequency metrology is migrating at a fast pace towards optical signals because higher frequencies are easier to measure accurately. Optical frequency metrology is strongly articulated around frequency combs, a special kind of laser that emit stable and repetitive short pulses and that can be used to link electrical frequencies, such as provided by an atomic clock, to optical frequencies. Combs thus allow measuring optical frequencies in an absolute manner by comparing them to the caesium signal. A world-class optics and photonics laboratory working in optical metrology and developing short-pulse lasers therefore absolutely needs a state-of-the-art frequency standard. Frequency combs are precise optical sources that promise revolutions in several domains besides metrology. The first and foremost is probably in optical spectroscopy, the science of determining the chemical composition of gases, liquids and solids by measuring the interaction of light at different wavelengths with matter. When you drink milk, its purity has been assessed using a spectrometer and when you check the weather forecasts to plan a long weekend, you are effectively making use of several spectrometers on satellites. Atomic clocks are also important in telecommunications to synchronize data signals to the highest level. Caesium standards are therefore installed in telecommunication central offices, making sure all the bits enter the Internet channels with the right timing. It is therefore natural that researchers working in faster, better and more efficient communication systems also need the best possible clock to synchronize their signals. The research groups of eight faculty members with more than 30 graduate students have a direct short time use for the atomic clock. The services provided by the caesium standard will moreover be available to over 20 professors and 300 students.