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Cold and Trapped: Using Lasers to Approach Absolute Zero - Dr Andrew Pratt

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P/L/001

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University of York

York

YO10 5DD

United Kingdom

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“Cold and Trapped: Using Lasers to Approach Absolute Zero”

Given the rude interuption of a poorly timed fire alarm in his last attempt to give this lecture, Physsoc invites back Doctor Andrew Pratt from the York Physics Department. Here he will give (this time) a full explanation of how lasers can be used to cool objects - something not usually associated with them. Below is a summary of the lecture, along with a few figures, from Doctor Pratt to pique your interest.

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.

The figure shows an image of Sisyphus, a mythological king forever destined to roll a massive boulder to the top of a hill, only for it to continually roll back down again. Lasers can be used to create analogous ‘hills’ which allows atoms to be trapped and then cooled to ultralow temperatures.Some lecture spoilers
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P/L/001

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University of York

York

YO10 5DD

United Kingdom

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