How long does a particle take to quantum-mechanically tunnel through a barrier? Physicists have pondered this question since tunnelling was first identified 90 years ago. In this episode of the Physics World Weekly podcast, Aephraim Steinberg of the University of Toronto explains how his team used the spins of ultracold atoms to measure how long it took for the atoms to tunnel through an optical barrier. Steinberg also chats about the importance of understanding the concept of measurement in quantum mechanics.
Later in this episode, Physics World’s Tami Freeman explains how relatively inexpensive fitness tracker watches could help monitor breathing during sleep. Our Madrid correspondent James Dacey is also on hand to talk about how quantum dots could help preserve ancient stone monuments and we marvel at a stunning new telescope image of two huge exoplanets orbiting a Sun-like star.