The question of how long a tunneling particle spends in the forbidden region of a barrier has been a perplexingpuzzle in foundational quantum mechanics for many decades. The Larmor time, one de nition of tunneling time,uses an auxiliary degree of freedom of the tunneling particles to clock the time spent inside the barrier. Recently,we made our first measurement of the Larmor time for Bose-condensed 87Rb atoms tunneling through an opticalbarrier.1 Here, we report on follow up measurements with improved precision in the measured times and alsostudy the time for the reected atomic cloud. We observe signi cant discrepancies between our results and asimple theory based on weak measurement. We discuss our ndings, hypothesize explanations for our results,and suggest future studies.
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