Characteristic time-scales for macroscopic quantum tunneling

Abstract Tunneling time ( τ t ) , in its real and imaginary parts, can be deduced from measurements of decay time ( τ d ) in Josephson junctions. It turns out that the real part of τ t is much shorter than the imaginary one, which can be identified with the semiclassical time. A third quantity is the Zeno-time ( τ Z ) which, in turn, can be estimated from the previous ones, since it is approximately given by their geometrical mean. The possibility of observing the Zeno-effect is then discussed.