‘It’s the perfect place’: London Underground hosts

Subatomic instrument will be able to accurately pinpoint locations under ground and under water, where satellite signals are often blocked

Dr Joseph Cotter takes some unusual pieces of luggage on his trips on the London underground. They include a stainless steel vacuum chamber, a few billion atoms of rubidium and an array of lasers that are used to cool his equipment to a temperature just above absolute zero.

While not the average kit you would expect to find being dragged into carriages on the District Line, this is the gear that Cotter – who works at Imperial College London’s Centre for Cold Matter – uses on his underground travels.