Torrontegui Muñoz, ErikMuga, Juan GonzaloMartorell, JoanSprung, Donald W. L.2021-04-082021-04-082009-07-10Physical review A, 80(1), 012703, July 2009, 8 pp.1050-29471094-1622 (online)https://hdl.handle.net/10016/32315We study the elusive transition from exponential to postexponential (algebraic) decay of the probability density of a quantum particle emitted by an exponentially decaying source in one dimension. The main finding is that the probability density at the transition time, and thus its observability, increases with the distance of the detector from the source up to a critical distance beyond which exponential decay is no longer observed. Solvable models provide explicit expressions for the dependence of the transition on resonance and observational parameters, facilitating the choice of optimal conditions.8eng© 2009 American Physical SocietyExponential decayTunneling timeDiffractionSpaceresearch articleFísicahttp://dx.doi.org/10.1103/PhysRevA.80.012703open access11, 0127038PHYSICAL REVIEW A80AR/0000026503