31 research outputs found
Quantum photon emission from a moving mirror in the nonperturbative regime
We consider the coupling of the electromagnetic vacuum field with an
oscillating perfectly-reflecting mirror in the nonrelativistic approximation.
As a consequence of the frequency modulation associated to the motion of the
mirror, low frequency photons are generated. We calculate the photon emission
rate by following a nonperturbative approach, in which the coupling between the
field sidebands is taken into account. We show that the usual perturbation
theory fails to account correctly for the contribution of TM-polarized vacuum
fluctuations that propagate along directions nearly parallel to the plane
surface of the mirror.
As a result of the modification of the field eigenfunctions, the resonance
frequency for photon emission is shifted from its unperturbed value.Comment: 11 pages, 3 figures. To be published in Optics Communication
Quantum radiation pressure on a moving mirror at finite temperature
We compute the radiation pressure force on a moving mirror, in the
nonrelativistic approximation, assuming the field to be at temperature At
high temperature, the force has a dissipative component proportional to the
mirror velocity, which results from Doppler shift of the reflected thermal
photons. In the case of a scalar field, the force has also a dispersive
component associated to a mass correction. In the electromagnetic case, the
separate contributions to the mass correction from the two polarizations
cancel. We also derive explicit results in the low temperature regime, and
present numerical results for the general case. As an application, we compute
the dissipation and decoherence rates for a mirror in a harmonic potential
well.Comment: Figure 3 replaced, changes mainly in Sections IV and V, new appendix
introduced. To appear in Physical Review
Motion-Induced Radiation from a Dynamically Deforming Mirror
A path integral formulation is developed to study the spectrum of radiation
from a perfectly reflecting (conducting) surface. It allows us to study
arbitrary deformations in space and time. The spectrum is calculated to second
order in the height function. For a harmonic traveling wave on the surface, we
find many different regimes in which the radiation is restricted to certain
directions. It is shown that high frequency photons are emitted in a beam with
relatively low angular dispersion whose direction can be controlled by the
mechanical deformations of the plate.Comment: 4 pages, 2 eps figues included, final version as appeared in PR
Fluctuations, dissipation and the dynamical Casimir effect
Vacuum fluctuations provide a fundamental source of dissipation for systems
coupled to quantum fields by radiation pressure. In the dynamical Casimir
effect, accelerating neutral bodies in free space give rise to the emission of
real photons while experiencing a damping force which plays the role of a
radiation reaction force. Analog models where non-stationary conditions for the
electromagnetic field simulate the presence of moving plates are currently
under experimental investigation. A dissipative force might also appear in the
case of uniform relative motion between two bodies, thus leading to a new kind
of friction mechanism without mechanical contact. In this paper, we review
recent advances on the dynamical Casimir and non-contact friction effects,
highlighting their common physical origin.Comment: 39 pages, 4 figures. Review paper to appear in Lecture Notes in
Physics, Volume on Casimir Physics, edited by Diego Dalvit, Peter Milonni,
David Roberts, and Felipe da Rosa. Minor changes, a reference adde
Dynamical Casimir effect without boundary conditions
The moving-mirror problem is microscopically formulated without invoking the
external boundary conditions. The moving mirrors are described by the quantized
matter field interacting with the photon field, forming dynamical cavity
polaritons: photons in the cavity are dressed by electrons in the moving
mirrors. The effective Hamiltonian for the polariton is derived, and
corrections to the results based on the external boundary conditions are
discussed.Comment: 12 pages, 2 figure
Quantum phase gate with a selective interaction
We present a proposal for implementing quantum phase gates using selective
interactions. We analize selectivity and the possibility to implement these
gates in two particular systems, namely, trapped ions and Cavity QED.Comment: Four pages of TEX file and two EPS figures. Submitted for publicatio
Quantum electromagnetic field in a three dimensional oscillating cavity
We compute the photon creation inside a perfectly conducting, three
dimensional oscillating cavity, taking the polarization of the electromagnetic
field into account. As the boundary conditions for this field are both of
Dirichlet and (generalized) Neumann type, we analyze as a preliminary step the
dynamical Casimir effect for a scalar field satisfying generalized Neumann
boundary conditions. We show that particle production is enhanced with respect
to the case of Dirichlet boundary conditions. Then we consider the transverse
electric and transverse magnetic polarizations of the electromagnetic field.
For resonant frequencies, the total number of photons grows exponentially in
time for both polarizations, the rate being greater for transverse magnetic
modes.Comment: 11 pages, 1 figur
Vacuum local and global electromagnetic self-energies for a point-like and an extended field source
We consider the electric and magnetic energy densities (or equivalently field
fluctuations) in the space around a point-like field source in its ground
state, after having subtracted the spatially uniform zero-point energy terms,
and discuss the problem of their singular behavior at the source's position. We
show that the assumption of a point-like source leads, for a simple Hamiltonian
model of the interaction of the source with the electromagnetic radiation
field, to a divergence of the renormalized electric and magnetic energy density
at the position of the source. We analyze in detail the mathematical structure
of such singularity in terms of a delta function and its derivatives. We also
show that an appropriate consideration of these singular terms solves an
apparent inconsistency between the total field energy and the space integral of
its density. Thus the finite field energy stored in these singular terms gives
an important contribution to the self-energy of the source. We then consider
the case of an extended source, smeared out over a finite volume and described
by an appropriate form factor. We show that in this case all divergences in
local quantities such as the electric and the magnetic energy density, as well
as any inconsistency between global and space-integrated local self-energies,
disappear.Comment: 8 pages. The final publication is available at link.springer.co
Metallo-dielectric diamond and zinc-blende photonic crystals
It is shown that small inclusions of a low absorbing metal can have a
dramatic effect on the photonic band structure. In the case of diamond and
zinc-blende photonic crystals, several complete photonic band gaps (CPBG's) can
open in the spectrum, between the 2nd-3rd, 5th-6th, and 8th-9th bands. Unlike
in the purely dielectric case, in the presence of small inclusions of a low
absorbing metal the largest CPBG for a moderate dielectric constant
(epsilon<=10) turns out to be the 2nd-3rd CPBG. The 2nd-3rd CPBG is the most
important CPBG, because it is the most stable against disorder. For a diamond
and zinc-blende structure of nonoverlapping dielectric and metallo-dielectric
spheres, a CPBG begins to decrease with an increasing dielectric contrast
roughly at the point where another CPBG starts to open--a kind of gap
competition. A CPBG can even shrink to zero when the dielectric contrast
increases further. Metal inclusions have the biggest effect for the dielectric
constant 2<=epsilon<=12, which is a typical dielectric constant at near
infrared and in the visible for many materials, including semiconductors and
polymers. It is shown that one can create a sizeable and robust 2nd-3rd CPBG at
near infrared and visible wavelengths even for a photonic crystal which is
composed of more than 97% low refractive index materials (n<=1.45, i.e., that
of silica glass or a polymer). These findings open the door for any
semiconductor and polymer material to be used as genuine building blocks for
the creation of photonic crystals with a CPBG and significantly increase the
possibilities for experimentalists to realize a sizeable and robust CPBG in the
near infrared and in the visible. One possibility is a construction method
using optical tweezers, which is analyzed here.Comment: 25 pp, 23 figs, RevTex, to appear in Phys Rev B. For more information
look at
http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm