Numerical investigation of photon creation in a three-dimensional resonantly vibrating cavity: TE-modes

The creation of TE-mode photons in a three-dimensional perfectly conducting cavity with one resonantly vibrating wall is studied numerically. We show that the creation of TE-mode photons in a rectangular cavity is related to the production of massive scalar particles on a time-dependent interval. The equations of motion are solved numerically which allows to take into account the intermode coupling. We compare the numerical results with analytical predictions and discuss the effects of the intermode coupling in detail. The numerical simulations reveal that photon creation in a three-dimensional resonantly vibrating cavity can be maximized by arranging the size of the cavity such that certain conditions are realized. In particular, the creation of TE-mode photons in the lowest frequency mode $(1,1,1)$ is most efficient in a non-cubic cavity where the size of the non-dynamical dimensions is roughly 11 times larger than the size of the dynamical dimension. We discuss this effect and its relation to the intermode coupling in detail.Comment: 14 pages, 18 figures, revised version, typos corrected, references added, title changed with respect to older version, submitted to Phys. Rev.

The dynamical Casimir effect in braneworlds

In braneworld cosmology the expanding Universe is realized as a brane moving through a warped higher-dimensional spacetime. Like a moving mirror causes the creation of photons out of vacuum fluctuations, a moving brane leads to graviton production. We show that, very generically, Kaluza-Klein (KK) particles scale like stiff matter with the expansion of the Universe and can therefore not represent the dark matter in a warped braneworld. We present results for the production of massless and KK gravitons for bouncing branes in five-dimensional anti de Sitter space. We find that for a realistic bounce the back reaction from the generated gravitons will be most likely relevant. This letter summarizes the main results and conclusions from numerical simulations which are presented in detail in a long paper [M.Ruser and R. Durrer, Phys. Rev. D 76, 104014 (2007), arXiv:0704.0790]Comment: misprints corrected, matches published versio

Numerical approach to the dynamical Casimir effect

The dynamical Casimir effect for a massless scalar field in 1+1-dimensions is studied numerically by solving a system of coupled first-order differential equations. The number of scalar particles created from vacuum is given by the solutions to this system which can be found by means of standard numerics. The formalism already used in a former work is derived in detail and is applied to resonant as well as off-resonant cavity oscillations.Comment: 15 pages, 4 figures, accepted for publication in J. Phys. A (special issue: Proceedings of QFEXT05, Barcelona, Sept. 5-9, 2005

Dynamical Casimir effect for gravitons in bouncing braneworlds

We consider a two-brane system in a five-dimensional anti-de Sitter spacetime. We study particle creation due to the motion of the physical brane which first approaches the second static brane (contraction) and then recedes from it(expansion). The spectrum and the energy density of the generated gravitons are calculated. We show that the massless gravitons have a blue spectrum and that their energy density satisfies the nucleosynthesis bound with very mild constraints on the parameters. We also show that the Kaluza-Klein modes cannot provide the dark matter in an anti-de-Sitter braneworld. However, for natural choices of parameters, backreaction from the Kaluza-Klein gravitons may well become important. The main findings of this work have been published in the form of a Letter [R. Durrer and M. Ruser, Phys. Rev. Lett. 99, 071601 (2007), arXiv:0704.0756].Comment: 40 pages, 34 figures, improved and extended version, matches published versio

Graviton production in anti-de Sitter braneworld cosmology: A fully consistent treatment of the boundary condition

In recent work by two of us, [Durrer & Ruser, PRL 99, 071601 (2007); Ruser & Durrer PRD 76, 104014 (2007)], graviton production due to a moving spacetime boundary (braneworld) in a five dimensional bulk has been considered. In the same way as the presence of a conducting plate modifies the electromagnetic vacuum, the presence of a brane modifies the graviton vacuum. As the brane moves, the time dependence of the vacuum leads to particle creation via the so called 'dynamical Casimir effect'. In our previous work a term in the boundary condition which is linear in the brane velocity has been neglected. In this work we develop a new approach which overcomes this approximation. We show that the previous results are not modified if the brane velocity is low.Comment: 13 pages, 6 figures, added a clarifying paragraph about the setup, the brane motion adapted w.r.t the version published in PR

On graviton production in braneworld cosmology

We study braneworlds in a five dimensional bulk, where cosmological expansion is mimicked by motion through AdS$_5$. We show that the five dimensional graviton reduces to the four dimensional one in the late time approximation of such braneworlds. Inserting a fixed regulator brane far from the physical brane, we investigate quantum graviton production due to the motion of the brane. We show that the massive Kaluza-Klein modes decouple completely from the massless mode and they are not generated at all in the limit where the regulator brane position goes to infinity. In the low energy limit, the massless four dimensional graviton obeys the usual 4d equation and is therefore also not generated in a radiation-dominated universe.Comment: 9 pages, minor changes, references correcte

Vibrating Cavities - A numerical approach

We present a general formalism allowing for efficient numerical calculation of the production of massless scalar particles from vacuum in a one-dimensional dynamical cavity, i.e. the dynamical Casimir effect. By introducing a particular parametrization for the time evolution of the field modes inside the cavity we derive a coupled system of first-order linear differential equations. The solutions to this system determine the number of created particles and can be found by means of numerical methods for arbitrary motions of the walls of the cavity. To demonstrate the method which accounts for the intermode coupling we investigate the creation of massless scalar particles in a one-dimensional vibrating cavity by means of three particular cavity motions. We compare the numerical results with analytical predictions as well as a different numerical approach.Comment: 28 pages, 19 figures, accepted for publication in J. Opt. B: Quantum Semiclass. Op

Dynamical Casimir effect : from photon creation in dynamical cavities to graviton production in braneworlds

La présence de champs externes peut modifier les propriétés du vide et induire des réactions intéressantes. Un phénomène particulièrement intéressant est la réaction du champ du vide à des champs de background qui varient avec le temps. Le vide répond à de telles perturbations dépendantes du temps par l'amplification des fluctuations du vide qui peuvent être interprétées comme la création de particules à partir du vide. Les conditions de bord du système, qui peuvent être considérées comme des champs classiques de background très localisés, ont un impact particulier sur le champ du vide, ils changent la structure de ses modes. Ceci a comme conséquence une force attractive entre deux plaques métalliques appelé l'effet Casimir statique, ainsi que la création de photons par des miroirs en mouvement, appelé l'effet Casimir dynamique. Cette thèse étudie l'effet Casimir dynamique pour deux scénarios: premièrement la production de photons dans une cavité dynamique et deuxièment la production de gravitons par des branes en mouvement