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Astrid Lambrecht

Publications and source records attributed to Astrid Lambrecht.

At least 73 records · Page 4Linked to original sources
arXiv2004

Roughness correction to the Casimir force : Beyond the Proximity Force Approximation

We calculate the roughness correction to the Casimir effect in the parallel plates geometry for metallic plates described by the plasma model. The calculation is perturbative in the roughness amplitude with arbitrary values for the plasma wavelength, the plate separation and the roughness correlation length. The correction is found to be always larger than the result obtained in the Proximity Force Approximation.

quant-ph↗
arXiv2004

Electromagnetic vacuum fluctuations, Casimir and Van der Waals forces

Electromagnetic vacuum fluctuations have observable consequences, like the Casimir force between mirrors in vacuum. This force is now measured with good accuracy and agreement with theory when the effect of imperfect reflection of mirrors is properly taken into account. We discuss the simple case of bulk metallic mirrors described by a plasma model and show that simple scaling laws are obtained at the limits of long and short distances. The crossover between the short and long-distance laws is quite similar to the crossover between Van der Waals and Casimir-Polder forces for two atoms in vacuum. The result obtained at short distances can be understood as the London interaction between plasmon excitations at the surface of each bulk mirror.

quant-ph↗
arXiv2003

The Casimir force between real mirrors at non zero temperature

The Casimir force between dissipative metallic mirrors at non zero temperature has recently given rise to contradictory claims which have raised doubts about the theoretical expression of the force. In order to contribute to the resolution of this difficulty, we come back to the derivation of the force from basic principles of the quantum theory of lossy optical cavities. We obtain an expression which is valid for arbitrary mirrors, including dissipative ones, characterized by frequency dependent reflection amplitudes.

quant-ph↗
arXiv2003

HYPER and gravitational decoherence

We study the decoherence process associated with the scattering of stochastic backgrounds of gravitational waves. We show that it has a negligible influence on HYPER-like atomic interferometers although it may dominate decoherence of macroscopic motions, such as the planetary motion of the Moon around the Earth.

quant-ph↗
arXiv2003

The Casimir force between rough metallic plates

The Casimir force between two metallic plates is affected by their roughness state. This effect is usually calculated through the so-called `proximity force approximation' which is only valid for small enough wavevectors in the spectrum of the roughness profile. We introduce here a more general description with a wavevector-dependent roughness sensitivity of the Casimir effect. Since the proximity force approximation underestimates the effect, a measurement of the roughness spectrum is needed to achieve the desired level of accuracy in the theory-experiment comparison.

quant-ph↗
arXiv2003

The Casimir force and the quantum theory of lossy optical cavities

We present a new derivation of the Casimir force between two parallel plane mirrors at zero temperature. The two mirrors and the cavity they enclose are treated as quantum optical networks. They are in general lossy and characterized by frequency dependent reflection amplitudes. The additional fluctuations accompanying losses are deduced from expressions of the optical theorem. A general proof is given for the theorem relating the spectral density inside the cavity to the reflection amplitudes seen by the inner fields. This density determines the vacuum radiation pressure and, therefore, the Casimir force. The force is obtained as an integral over the real frequencies, including the contribution of evanescent waves besides that of ordinary waves, and, then, as an integral over imaginary frequencies. The demonstration relies only on general properties obeyed by real mirrors which also enforce general constraints for the variation of the Casimir force.

quant-ph↗
arXiv2002

Casimir effect and vacuum energy

Vacuum fluctuations have observable consequences, like the Casimir force appearing between two mirrors in vacuum. This force is now measured with good accuracy and agreement with theory. We discuss the meaning and consequences of these statements by emphasizing their relation with the problem of vacuum energy, one of the main unsolved problems at the interface between gravitational and quantum theory.

quant-ph↗
arXiv2001

Correlation between plasma and temperature corrections to the Casimir force

When comparing experimental results with theoretical predictions of the Casimir force, the accuracy of the theory is as important as the precision of experiments. Here we evaluate the Casimir force when finite conductivity of the reflectors and finite temperature are simultaneously taken into account. We show that these two corrections are correlated, i.e. that they can not, in principle, be evaluated separately and simply multiplied. We estimate the correlation factor which measures the deviation from this common approximation. We focus our attention on the case of smooth and plane plates with a metallic optical response modeled by a plasma model.

quant-ph↗
arXiv2001

Decoherence and gravitational backgrounds

We study the decoherence process associated with the scattering of stochastic gravitational waves. We discuss the case of macroscopic systems, such as the planetary motion of the Moon around the Earth, for which gravitational scattering is found to dominate decoherence though it has a negligible influence on damping. This contrast is due to the very high effective temperature of the background of gravitational waves in our galactic environment.

gr-qc↗
arXiv2001

Quantum vacuum fluctuations

The existence of irreducible field fluctuations in vacuum is an important prediction of quantum theory. These fluctuations have many observable consequences, like the Casimir effect which is now measured with good accuracy and agreement with theory, provided that the latter accounts for differences between real experiments and the ideal situation considered by Casimir. But the vacuum energy density calculated by adding field mode energies is much larger than the density observed around us through gravitational phenomena. This ``vacuum catastrophe'' is one of the unsolved problems at the interface between quantum theory on one hand, inertial and gravitational phenomena on the other hand. It is however possible to put properly formulated questions in the vicinity of this paradox. These questions are directly connected to observable effects bearing upon the principle of relativity of motion in quantum vacuum.

quant-ph↗
arXiv2001

Relativity of motion in quantum vacuum

The problem of relativity of motion in quantum vacuum is addressed by considering a cavity moving in vacuum in a monodimensional space. The cavity is an open system which emits photons when it oscillates in vacuum. Qualitatively new effects like pulse shaping in the time domain and frequency conversion in the spectrum may help to discrimate motion-induced radiation from potential stray effects.

quant-ph↗
arXiv2001

The Casimir force between metallic mirrors

In order to compare recent experimental results with theoretical predictions we study the influence of finite conductivity of metals on the Casimir effect. The correction to the Casimir force and energy due to imperfect reflection and finite temperature are evaluated for plane metallic plates where the dielectric functions of the metals are modeled by a plasma model. The results are compared with the common approximation where conductivity and thermal corrections are evaluated separately and simply multiplied.

quant-ph↗
arXiv2001

Gravitational decoherence of planetary motions

We study the effect of the scattering of gravitational waves on planetary motions, say the motion of the Moon around the Earth. Though this effect has a negligible influence on dissipation, it dominates fluctuations and the associated decoherence mechanism, due to the very high effective temperature of the background of gravitational waves in our galactic environment.

quant-ph↗
arXiv2000

Temperature dependence of the Casimir effect between metallic mirrors

We calculate the Casimir force and free energy for plane metallic mirrors at non-zero temperature. Numerical evaluations are given with temperature and conductivity effects treated simultaneously. The results are compared with the approximation where both effects are treated independently and the corrections simply multiplied. The deviation between the exact and approximated results takes the form of a temperature dependent function for which an analytical expression is given. The knowledge of this function allows simple and accurate estimations at the % level.

quant-ph↗
arXiv1999

Casimir force between metallic mirrors

We study the influence of finite conductivity of metals on the Casimir effect. We put the emphasis on explicit theoretical evaluations which can help comparing experimental results with theory. The reduction of the Casimir force is evaluated for plane metallic plates. The reduction of the Casimir energy in the same configuration is also calculated. It can be used to infer the reduction of the force in the plane-sphere geometry through the `proximity theorem'. Frequency dependent dielectric response functions of the metals are represented either by the simple plasma model or, more accurately, by using the optical data known for the metals used in recent experiments, that is Al, Au and Cu. In the two latter cases, the results obtained here differ significantly from those published recently.

quant-ph↗
arXiv1998

Relativity of Motion in Vacuum

The existence of vacuum fluctuations leads to reconsider the question of relativity of motion. The present article is devoted to this aim with a main line which can be formulated as follows: ``The principle of relativity of motion is directly related to symmetries of quantum vacuum''. Keeping close to this statement, we discuss the controversial relation between vacuum and motion. We introduce the question of relativity of motion in its historical development before coming to the results obtained more recently.

quant-ph↗
arXiv1997

Thermodynamics of non-interacting Bosons in low-dimensional potentials

On the basis of a macroscopic ground state population it was argued recently that Bose-Einstein condensation should occur in a one-dimensional harmonic potential. We examine this situation by drawing analogies to Bosons in a two-dimensional box, where the thermodynamic limit is well-defined. We show that in both systems although the ground state populations show sharp onsets at the critical temperature, the behaviour of the specific heat is analytic, which proves the absence of a phase transition in these systems.

cond-mat.stat-mech↗