Measuring lifetime of correspondence with classical decay of correlation in quantum chaos.

A very weakly coupled linear oscillator is proposed as a detector for observing time-irreversible characteristics of a quantum system, and it is used to measure the lifetime during which a classically chaotic quantum system shows decay of correlation. Except for a particular case where the lifetime agrees with the conventional Heisenberg time, which is proportional to the Hilbert space dimension N, it is in general much longer: the lifetime increases in proportion to the product of N and the number of superposed eigenstates, and is proportional to N² in the case of full superposition. [ABSTRACT FROM AUTHOR]