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Cold and Trapped: Using Lasers to Approach Absolute Zero - Dr Andrew Pratt
Tue 25 April 2017, 19:00 – 20:00 BST
Our everyday experience tells us that if light shines on an object, then that object will heat up, as happens when the Sun’s rays warm our skin. However, lasers, the most powerful sources of light, can actually be used to cool atoms down to within a millionth of a degree of the lowest temperature that is theoretically possible, known as absolute zero (−273.15° Celsius or zero Kelvin). Over five decades, ever more sophisticated techniques, with exotic names such as Sisyphus cooling and optical molasses, have been developed that allow colder and colder temperatures to be reached. Such low temperatures are necessary to make improved measurements of the most fundamental properties of nature and for applications such as metrology and the atomic clocks used in global positioning systems (e.g. GPS). Exciting new technologies are also being explored such as quantum computers and lasers actually made of atoms instead of light. This talk will introduce the concept of ‘laser cooling’, the schemes used to achieve colder and colder temperatures, and how this field benefits our everyday lives.