2,634 research outputs found
Pulse propagation, population transfer and light storage in five-level media
We consider adiabatic interaction of five-level atomic systems and their
media with four short laser pulses under the condition of all two-photon
detunings being zero. We derive analytical expressions for eigenvalues of the
system's Hamiltonian and determine conditions of adiabaticity for both the atom
and the medium. We analyse, in detail, the system's behaviour when the
eigenvalue with non-vanishing energy is realized. As distinct from the usual
dark state of a five-level system (corresponding to zero eigenvalue), which is
a superposition of three states, in our case the superposition of four states
does work. This seemingly unfavourable case is nevertheless demonstrated to
imitate completely a three-level system not only for a single atom but also in
the medium, since the propagation equations are also split into those for
three- and two-level media separately. We show that, under certain conditions,
all the coherent effects observed in three-level media, such as population
transfer, light slowing, light storage, and so on, may efficiently be realized
in five-level media. This has an important advantage that the light storage can
be performed twice in the same medium, i.e., the second pulse can be stored
without retrieving the first one, and then the two pulses can be retrieved in
any desired sequence
Pseudoclassical theories of Majorana, Weyl and Majorana--Weyl particles
A pseudoclassical theories of Majorana, Weyl and Majorana--Weyl particles in
the space--time dimensions are constructed. The canonical quantization
of these theories is carried out and as a result we obtain the quantum
mechanical description of neutral particle in , Weyl particle in
and neutral Weyl particle in . In dimensional
space--time the description of the neutral particle coincides with the field
theoretical description of the Majorana particle in the Foldy--Wouthuysen
representation. In dimensions the neutral Weyl particle coincides with
the Majorana--Weyl particle in the Foldy--Wouthuysen representation.Comment: LATEX, 17 pages, no figure
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