68 research outputs found
Spontaneous Emission from a Fractal Vacuum
Spontaneous emission of a quantum emitter coupled to a QED vacuum with a
deterministic fractal structure of its spectrum is considered. We show that the
decay probability does not follow a Wigner-Weisskopf exponential decrease but
rather an overall power law behavior with a rich oscillatory structure, both
depending on the local fractal properties of the vacuum spectrum. These results
are obtained by giving first a general perturbative derivation for short times.
Then we propose a simplified model which retains the main features of a fractal
spectrum to establish analytic expressions valid for all time scales. Finally,
we discuss the case of a Fibonacci cavity and its experimental relevance to
observe these results.Comment: 5 pages, 2 figure
Level curvatures, spectral statistics and scaling for interacting particles
The mobility of two interacting particles in a random potential is studied,
using the sensitivity of their levels to a change of boundary conditions. The
delocalization in Hilbert space induced by the interaction of the two particle
Fock states is shown to decrease the mobility in metals and to increase it in
insulators. In contrast to the single particle case, the spectral rigidity is
not directly related to the level curvature. Therefore, another curvature of
topological origin is introduced, which defines the energy scale below which
the spectrum has the universal Wigner-Dyson rigidity.Comment: 4 pages, RevTe
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