  We put forward several inherently quantum characteristics of the dwell time,
and propose an operational method to detect them. The quantum dwell time is
pointed out to be a conserved quantity, totally bypassing Pauli's theorem.
Furthermore, the quantum dwell time in a region for one dimensional motion is
doubly degenerate. In presence of a potential barrier, the dwell time becomes
bounded, unlike the classical quantity. By using off-resonance coupling to a
laser we propose an operational method to measure the absorption by a complex
potential, and thereby the average time spent by an incoming atom in the laser
region.
