Distributed caesium frequency standard

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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.