Download F.S.S. Rosa

Spontaneous emission of an
atom near a wedge
F. S. S. Rosa
Los Alamos National Laboratory
Work in collaboration with T.N.C. Mendes,
C. Farina and A. Tenorio
Plan of the talk
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Introduction
The method
An atom inside a wedge
The spontaneous emission rate
Final remarks
Introduction
“A splendid light has dawned on me
about the absorption and emission of
radiation.”
A. Einstein
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QED (1927) :
Spontaneous emission and boundary
conditions - Theory
Parallel polarization
Normal polarization
G. Barton (1970),
P. Stehle (1970),
P.W. Milonni and P.L. Knight (1973),
M.R. Philpott (1973).
Experiments
• Feher et al. (1958) - microwave range
• Drexhage et al. (1968) - visible range
An experiment on suppression - Jhe et al. (1987)
Beam of
atoms
Oven
Conducting plates
Detector
The results
The method
• We use a master equation approach developed
by Dalibard, Dupont-Roc and Cohen-Tannoudji to
describe a particle (in our case, an atom)
interacting with a reservoir (the radiation field).
• This approach provides general expressions
for the atomic energy shifts and the exchange
rates.
Using some reasonable approximations for the master
equation, we get
transition rate
energy shift
Some important expressions
}
}
=
=
An atom inside a wedge
R
Some Motivations
•
The wedge has been used for some important
measurements of the van der Waals force.
•
It is the most soft departing from the plane
geometry, and its relative simplicity allows some
analytical calculations.
• To use an alternative method that gives
expressions valid in both retarded and nonretarded regimes.
The excited potential
Graphic results
 = /3
 = /5
 = /8
The spontaneous emission
rate
Graphic results
From another perspective
Suppressed emission
 = /3
y
PP
NP
/2
0.24 
 = /12
 = /8
0.43 
PP
NP
0.4 
Final remarks
• Everything seems to be working fine for
the wedge setup.
• Refine our investigation: introduce
temperature and finite conductivity effects.
• Investigate the possibility of trapping
particles using the vacuum field.