187 research outputs found
Superbunching and Nonclassicality as new Hallmarks of Superradiance
Superradiance, i.e., spontaneous emission of coherent radiation by an
ensemble of identical two-level atoms in collective states introduced by Dicke
in 1954, is one of the enigmatic problems of quantum optics. The startling gist
is that even though the atoms have no dipole moment they radiate with increased
intensity in particular directions. Following the advances in our understanding
of superradiant emission by atoms in entangled states we examine the
quantum statistical properties of superradiance. Such investigations require
the system to have at least two excitations as one needs to explore the
photon-photon correlations of the radiation emitted by such states. We present
specifically results for the spatially resolved photon-photon correlations of
systems prepared in doubly excited states and give conditions when the
atomic system emits nonclassial light. Equally, we derive the conditions for
the occurrence of bunching and even of superbunching, a rare phenomenon
otherwise known only from nonclassical states of light like the squeezed
vacuum. We finally investigate the photon-photon cross correlations of the
spontaneously scattered light and highlight the nonclassicalty of such
correlations.Comment: 14 pages, 7 picture
Intensity-intensity correlations as a probe of interferences - under conditions of none in the intensity
The different behaviour of first order interferences and second order
correlations are investigated for the case of two coherently excited atoms. For
intensity measurements this problem is equivalent to Young's double slit
experiment and was investigated in an experiment by Eichmann et al. [Phys. Rev.
Lett. 70, 2359 (1993)] and later analyzed in detail by Itano et al. [Phys. Rev.
A 57, 4176 (1998)]. Our results show that in cases where the intensity
interferences disappear the intensity-intensity correlations can display an
interference pattern with a visibility of up to 100%. The contrast depends on
the polarization selected for the detection and is independent of the strength
of the driving field. The nonclassical nature of the calculated
intensity-intensity correlations is also discussed.Comment: 14 pages, 2 figure
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