How much time does a tunneling particle spend in a barrier? A Larmor clock, one proposal to answer this question, measures the interaction between the particle and the barrier region using the spin degree of freedom of the particle to clock the dwell time inside the barrier. We report on precise Larmor time measurements of a Bose-Einstein condensate of 87Rb atoms tunneling through an optical barrier. We observe that atoms generally spend less time tunneling through higher barriers and that this time decreases for lower energy particles, confirming longstanding predictions of tunneling times. In addition, we present evidence of spin waves generated in the reflected portion of the condensate. Due to the coincidence of scattering lengths in 87Rb, a BEC in a mixture of two hyperfine states behaves as a phase-coherent yet distinguishable two-component fluid. Reflection from the barrier creates a counter-propagating matter wave with spin partly transverse to the spin of the forward-going wave, initiating interaction-driven rotations due to the different interaction energies experienced by parallel versus anti-parallel spins. We observe one oscillation of a spin wave for low Rabi frequencies and study the transition where spin rotations become independent of the external coupling and instead are dominated by the interaction-driven effects.
|Presenter name||David Spierings|
|How will you attend ICAP-27?||I am planning on in-person attendance|