30 research outputs found
No quantum friction between uniformly moving plates
The Casimir forces between two plates moving parallel to each other are found
by calculating the vacuum electromagnetic stress tensor. The perpendicular
force between the plates is modified by the motion but there is no lateral
force on the plates. Electromagnetic vacuum fluctuations do not therefore give
rise to "quantum friction" in this case, contrary to previous assertions. The
result shows that the Casimir-Polder force on a particle moving at constant
speed parallel to a plate also has no lateral component.Comment: 17 pages. Final, published versio
Fiber-optical analogue of the event horizon
The physics at the event horizon resembles the behavior of waves in moving
media. Horizons are formed where the local speed of the medium exceeds the wave
velocity. We use ultrashort pulses in microstructured optical fibers to
demonstrate the formation of an artificial event horizon in optics. We observed
a classical optical effect, the blue-shifting of light at a white-hole horizon.
We also show by theoretical calculations that such a system is capable of
probing the quantum effects of horizons, in particular Hawking radiation.Comment: MEDIA EMBARGO. This paper is subject to the media embargo of Scienc
Metamaterial "Multiverse"
Optical space in metamaterials may be engineered to mimic the landscape of a
multidimensional Universe which has regions of different topology and different
effective dimensionality. The "metamaterial landscape" may include regions in
which one or two spatial dimensions are compactified. Nonlinear optics of
metamaterials in these regions mimics either U(1) or SU(2) Kaluza-Klein
theories having one or more kinds of effective charges. As a result, novel
"photon blockade" nonlinear optical metamaterial devices may be realized.
Topology-changing phase transitions in such metamaterials lead to considerable
particle creation perceived as flashes of light, thus providing a toy model of
birth of an individual physical Universe.Comment: 13 pages, 2 figures, this version is accepted for publication in the
Journal of Optic
General Relativity in Electrical Engineering
In electrical engineering metamaterials have been developed that offer
unprecedented control over electromagnetic fields. Here we show that general
relativity lends the theoretical tools for designing devices made of such
versatile materials. Given a desired device function, the theory describes the
electromagnetic properties that turn this function into fact. We consider media
that facilitate space-time transformations and include negative refraction. Our
theory unifies the concepts operating behind the scenes of perfect invisibility
devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic
analogs of the event horizon, and may lead to further applications
Divergence of Casimir stress in inhomogeneous media
Copyright © 2013 American Physical SocietyWe examine the local behavior of the regularized stress tensor commonly used in calculations of the Casimir force for a dielectric medium inhomogeneous in one direction. It is shown that the usual expression for the stress tensor is not finite anywhere within the medium, whatever the temporal dispersion or index profile, and that this divergence is unlikely to be removed through a simple modification to the regularization procedure. Our analytic argument is illustrated numerically for a medium approximated as a series of homogeneous strips, as the width of these strips is taken to zero. The findings hold for all magnetodielectric media
Black hole lasers in Bose-Einstein condensates
We consider elongated condensates that cross twice the speed of sound. In the
absence of periodic boundary conditions, the phonon spectrum possesses a
discrete and finite set of complex frequency modes that induce a laser effect.
This effect constitutes a dynamical instability and is due to the fact that the
supersonic region acts as a resonant cavity. We numerically compute the complex
frequencies and density-density correlation function. We obtain patterns with
very specific signatures. In terms of the gravitational analogy, the flows we
consider correspond to a pair of black hole and white hole horizons, and the
laser effect can be conceived as a self-amplified Hawking radiation. This is
verified by comparing the outgoing flux at early time with the standard black
hole radiation.Comment: iopams, 37 pages, 14 figures, 1 table; for associated gif animations,
see http://people.sissa.it/~finazzi/bec_bhlasers/movies/ or
http://iopscience.iop.org/1367-2630/12/9/095015/media. Published on New. J.
Phys. (http://iopscience.iop.org/1367-2630/12/9/095015/). V2: few new
comments, modified figure
Reply to comment on 'No quantum friction between uniformly moving plates'
we reply to the comment on our paper made by Volokitin and Persson (2011 New J. Phys. 13 068001).Publisher PDFPeer reviewe
General relativity in electrical engineering - art. no. 658104
In electrical engineering metamaterials have been developed that offer unprecedented control over electromagnetic fields. Here we show that general relativity lends the theoretical tools for designing devices made of such versatile materials. We consider media that facilitate space-time transformations and include negative refraction. Our theory unifies the concepts operating behind the scenes of perfect invisibility devices, perfect lenses, the optical Aharonov-Bohm effect and electromagnetic analogs of the event horizon, and may lead to further applications.</p