  Entanglement is usually associated with compound systems. We first show that
a one-dimensional (1D) completed scattering of a particle on a static potential
barrier represents an entanglement of two alternative one-particle
sub-processes, transmission and reflection, macroscopically distinct at the
final stage of scattering. The wave function for the whole ensemble of
scattering particles can be uniquely presented as the sum of two isometrically
evolved wave packets to describe the (to-be-)transmitted and (to-be-)reflected
subensembles of particles at all stages of scattering. A noninvasive
Larmor-clock timing procedure adapted to either subensemble shows that namely
the dwell time gives the time spent, on the average, by a particle in the
barrier region, and it denies the Hartman effect. As regards the group time, it
cannot be measured and hence it cannot be accepted as a measure of the
tunneling time. We argue that nonlocality of entangled states appears in
quantum mechanics due to inconsistency of its superposition principle with the
corpuscular properties of a particle. For example, this principle associates a
1D completed scattering with a single (one-way) process, while a particle, as
an indivisible object, cannot take part in transmission and reflection,
simultaneously.
