Events at Physics
By preparing ultracold Rubidium atoms in an atom waveguide and cooling them to approximately 1 nK, we are able to study tunneling across a 1-μm barrier formed by a blue-detuned laser beam. Using Raman coupling to generate a fictitious magnetic field, we let the spin of each atom act as a “clock” to record how long it spends in the barrier region. I will present our first results characterizing the tunneling time in this way. We analyze them in terms of the weak-measurement formalism, which makes it possible for one to discuss different “histories” for particles which end up in different final states. I will spend some time discussing this formalism more broadly, including problems it resolves and puzzles it raises.