EN
We show that phase space methods developed
for quantum mechanics, such as the Wigner distribution,
can be effectively used to study the evolution of nonstationary
noise in dispersive media. We formulate the issue
in terms of modes and show how modes evolve and
how they are effected by sources.We show that each mode
satisfies a Schrödinger type equation where the “Hamiltonian”
may not be Hermitian. The Hamiltonian operator
corresponds to dispersion relationwhere thewavenumber
is replaced by the wavenumber operator. A complex dispersion
relation corresponds to a non Hermitian operator
and indicates that we have attenuation. A number of examples
are given.