Astrid Lambrecht

Astrid Lambrecht
French National Centre for Scientific Research | CNRS · Institut de physique (INP)

PhD, HDR

About

196
Publications
18,932
Reads
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5,364
Citations
Additional affiliations
June 2018 - present
French National Centre for Scientific Research
Position
  • Managing Director
January 2016 - May 2018
French National Centre for Scientific Research
Position
  • Managing Director
September 2015 - December 2015
French National Centre for Scientific Research
Position
  • Consultant

Publications

Publications (196)
Article
We present a theoretical treatment of light scattering by an ensemble of N dipoles, taking into account recurrent multiple scattering. We study the intrinsic optical properties of collective dipolar systems without specifying a particular illumination condition. We apply this formalism to study the collective absorption modes for an ensemble of sma...
Preprint
We present a theoretical treatment of light scattering by an ensemble of N dipoles, taking into account recurrent multiple scattering. We study the intrinsic optical properties of collective dipolar systems without specifying a particular illumination condition. We apply this formalism to study the collective absorption modes for an ensemble of sma...
Article
We apply the scattering approach to the Casimir interaction between two dielectric half-spaces separated by an electrolyte solution. We take the nonlocal electromagnetic response of the intervening medium into account, which results from the presence of movable ions in solution. In addition to the usual transverse modes, we consider longitudinal ch...
Preprint
Full-text available
We apply the scattering approach to the Casimir interaction between two dielectric half-spaces separated by an electrolyte solution. We take the nonlocal electromagnetic response of the intervening medium into account, which results from the presence of movable ions in solution. In addition to the usual transverse modes, we consider longitudinal ch...
Article
Full-text available
We study the quantum reflection of ultracold antihydrogen atoms bouncing on the surface of a liquid helium bulk. The Casimir-Polder potential and quantum reflection are calculated and compared to the same quantities for other bulks. Antihydrogen can be protected from annihilation for as long as 1.3 s on a bulk of liquid ⁴He, and 1.7 s for liquid ³H...
Article
Full-text available
The Big Gravitational Spectrometer (BGS) takes advantage of the strong influence of the Earth's gravity on the motion of ultracold neutrons (UCNs) that makes it possible to shape and measure UCN spectra. We optimized the BGS to investigate the "small heating" of UCNs, that is the inelastic reflection of UCNs from a surface accompanied by an energy...
Article
Full-text available
We take dissipation into account in the derivation of the Casimir energy formula between two objects placed in a surrounding medium. The dissipation channels are considered explicitly in order to take advantage of the unitarity of the full scattering processes. We demonstrate that the Casimir energy is given by a scattering formula expressed in ter...
Article
Full-text available
We study the quantum reflection of ultracold antihydrogen atoms bouncing on the surface of a liquid helium film. The Casimir-Polder potential and quantum reflection are calculated for different thicknesses of the film supported by different substrates. Antihydrogen can be protected from anni- hilation for as long as 1.3s on a bulk of liquid 4He, an...
Article
An ultracold atom above a horizontal mirror experiences quantum reflection from the attractive Casimir-Polder interaction, which holds it against gravity and leads to quantum levitation states. We analyze this system by using a Liouville transformation of the Schrödinger equation and a Langer coordinate adapted to problems with a classical turning...
Article
Full-text available
We study the spatial fluctuations of the Casimir-Polder force experienced by an atom or a small sphere moved above a metallic plate at fixed separation distance. We discover that unlike the mean force, the magnitude of these fluctuations dramatically depends on the relaxation of conduction electron in the bulk, achieving values that differ by order...
Article
Full-text available
An ultracold atom above a horizontal mirror experiences quantum reflection from the attractive Casimir-Polder interaction, which holds it against gravity and leads to an effective quantum levitation. We analyze this system by using a Liouville transformation of the Schr\"odinger equation and a Langer coordinate adapted to problems with a classical...
Article
We study the energy spectrum of atoms trapped in a vertical one-dimensional optical lattice in close proximity to a reflective surface. We propose an effective model to describe the interaction between the atoms and the surface at any distance. Our model includes the long-range Casimir-Polder potential together with a short-range Lennard-Jones pote...
Article
Full-text available
We performed precision measurements of the probability of small heating and spectrum of UCNs up-scattered on the surface of hydrogen-free oil Fomblin Y-HVAC 18/8 as a function of temperature. The probability is well reproducible, does not depend on sample thickness and does not evolve in time. It is equal (9.8+-0.2)10^(-6) at the ambient temperatur...
Article
We reply to the "Comment on 'The Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors'" [arXiv:1604.06432]. We believe the comment misrepresents our papers, and fails to provide a plausible resolution to the conflict between theory and experiment.
Conference Paper
Full-text available
The aim of the GBAR (Gravitational Behavior of Antimatter at Rest) experiment is to measure the free fall acceleration of an antihydrogen atom, in the terrestrial gravitational field at CERN and therefore test the Weak Equivalence Principle with antimatter. The aim is to measure the local gravity with a 1% uncertainty which can be reduced to few pa...
Article
It has been increasingly becoming clear that Casimir and Casimir-Polder entropies may be negative in certain regions of temperature and separation. In fact, the occurrence of negative entropy seems to be a nearly ubiquitous phenomenon. This is most highlighted in the quantum vacuum interaction of a nanoparticle with a conducting plate or between tw...
Article
Full-text available
Do the laws of quantum physics still hold for macroscopic objects - this is at the heart of Schrödinger’s cat paradox - or do gravitation or yet unknown effects set a limit for massive particles? What is the fundamental relation between quantum physics and gravity? Ground-based experiments addressing these questions may soon face limitations due to...
Article
We present a time-dependent calculation of the velocity-dependent forces which act on an excited atomic dipole in relative motion with respect to ground state atoms of a different kind. Both, its interaction with a single atom and with a dilute atomic plate are evaluated. In either case, the total force consists of a conservative van der Waals comp...
Article
Full-text available
We study an effect of quenching of antihydrogen quantum states near material surface in the gravitational field of the Earth by local charges randomly distributed along the mirror surface. The quenching mechanism reduces the quantum reflection probability because of additional atom-charge interaction and nonadiabatic transitions to excited gravitat...
Article
Full-text available
The GBAR experiment will time the free fall of cold antihydrogen atoms dropped onto an annihilation plate to test the universality of free fall on antimatter. In this contribution, we study the quantum reflection of the anti-atom resulting from the Casimir-Polder attraction to the plate. We evaluate the Casimir-Polder potential and the associated q...
Article
We examine the conditions of validity for the Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic plane mirrors. As in the previously studied case of non-magnetic materials (Guerout et al, Phys. Rev. E 90 042125), we recover the usual expression for the lossy model of optical response, but not for the lossless plasma m...
Article
We explore the statistical properties of the Casimir-Polder potential between a dielectric sphere and a three-dimensional heterogeneous medium, by means of extensive numerical simulations based on the scattering theory of Casimir forces. The simulations allow us to confirm recent predictions for the mean and standard deviation of the Casimir potent...
Article
We investigate in detail the Casimir torque induced by quantum vacuum fluctuations between two nanostructured plates. Our calculations are based on the scattering approach and take into account the coupling between different modes induced by the shape of the surface which are neglected in any sort of proximity approximation or effective medium appr...
Article
Full-text available
The GBAR project (Gravitational Behaviour of Anti hydrogen at Rest) at CERN, aims to measure the free fall acceleration of ultracold neutral anti hydrogen atoms in the terrestrial gravitational field. The experiment consists preparing anti hydrogen ions (one antiproton and two positrons) and sympathetically cooling them with Be + ions to less than...
Article
Full-text available
We study the coherent effect of the Casimir-Polder interaction on the oscillations of two-photon driven atoms. We find that, for oscillations between two degenerate states in lambda-configuration, shifts on the Rabi frequency may be induced by non-additive level shifts. For oscillations between two Rydberg states in ladder-configuration, shifts on...
Article
Full-text available
We present a time-dependent quantum calculation of the van der Waals interaction between a pair of dissimilar atoms, one of which is initially excited while the other one is in its ground state. For small detuning, the interaction is predominantly mediated at all distances by the exchange of doubly resonant photons between the two atoms. We find th...
Article
Full-text available
Liouville transformations of Schr\"odinger equations preserve the scattering amplitudes while changing the effective potential. We discuss the properties of these gauge transformations and introduce a special Liouville gauge which allows one to map the problem of quantum reflection of an atom on an attractive Casimir-Polder well into that of reflec...
Article
Full-text available
Different experiments are ongoing to measure the effect of gravity on cold neutral antimatter atoms such as positronium, muonium, and antihydrogen. Among those, the project GBAR at CERN aims to measure precisely the gravitational fall of ultracold antihydrogen atoms. In the ultracold regime, the interaction of antihydrogen atoms with a surface is g...
Article
Full-text available
Liouville transformations map in a rigorous manner one Schrodinger equation into another, with a changed scattering potential. They are used here to transform quantum reflection of an atom on an attractive Casimir-Polder well into reflection of the atom on a repulsive wall. While the scattering properties are preserved, the corresponding semiclassi...
Article
Full-text available
We study the statistical fluctuations of the Casimir potential felt by an atom approaching a dielectric disordered medium. Starting from a microscopic model for the disorder, we calculate the variance of potential fluctuations in the limit of a weak density of heterogeneities. We show that fluctuations are essentially governed by scattering of the...
Article
Full-text available
We show that the Casimir-Polder interaction may induce coherent oscillations between degenerate atomic states. We illustrate this effect by computing the Casimir-Polder induced Rabi frequency on a $^{87}$Rb atom as it interacts with a reflecting surface and oscillates between two Zeeman sublevels of its ground state. This phenomenon is accompanied...
Article
Full-text available
Negative values of the Casimir entropy occur quite frequently at low temperatures in arrangements of metallic objects. The physical reason lies either in the dissipative nature of the metals as is the case for the plane-plane geometry or in the geometric form of the objects involved. Examples for the latter are the sphere-plane and the sphere-spher...
Article
Full-text available
Different experiments are ongoing to measure the effect of gravity on cold neutral antimatter atoms such as positronium, muonium and antihydrogen. Among those, the project GBAR in CERN aims to measure precisely the gravitational fall of ultracold antihydrogen atoms. In the ultracold regime, the interaction of antihydrogen atoms with a surface is go...
Article
Full-text available
Kelvin probe force microscopy at normal pressure was performed by two different groups on the same Au-coated planar sample used to measure the Casimir interaction in a sphere-plane geometry. The obtained voltage distribution was used to calculate the separation dependence of the electrostatic pressure $P_{\rm res}(D)$ in the configuration of the Ca...
Article
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Negative entropy has been known in Casimir systems for some time. For example, it can occur between parallel metallic plates modeled by a realistic Drude permittivity. Less well known is that negative entropy can occur purely geometrically, say between a perfectly conducting sphere and a conducting plate. The latter effect is most pronounced in the...
Article
Full-text available
We carefully re-examine the conditions of validity for the consistent derivation of the Lifshitz-Matsubara sum formula for the Casimir pressure between metallic plane mirrors. We recover the usual expression for the lossy Drude model, but not for the lossless plasma model. We give an interpretation of this new result in terms of the modes associate...
Article
The Casimir force is a spectacular consequence of the existence of vacuum fluctuations and thus deserves a place in courses on quantum theory. We argue that the scattering approach within a one-dimensional field theory is well suited to discuss the Casimir effect. It avoids in a transparent way divergences appearing in the evaluation of the vacuum...
Article
Full-text available
We study a method to induce resonant transitions between antihydrogen ($\bar{H}$) quantum states above a material surface in the gravitational field of the Earth. The method consists of applying a gradient of magnetic field, which is temporally oscillating with the frequency equal to a frequency of transition between gravitational states of antihyd...
Article
Full-text available
The Einstein classical Weak Equivalence Principle states that the trajectory of a particle is independent of its composition and internal structure when it is only submitted to gravitational forces. This fundamental principle has never been directly tested with antimatter. However, theoretical models such as supergravity may contain components indu...
Article
Full-text available
In the GBAR experiment, cold antihydrogen atoms will be left to fall on an annihilation plate with the aim of measuring the gravitational acceleration of antimatter. Here, we study the quantum reflection of these antiatoms due to the Casimir-Polder potential above the plate. We give realistic estimates of the potential and quantum reflection amplit...
Article
Full-text available
GBAR is a project aiming at measuring the free fall acceleration of gravity for antimatter, namely antihydrogen atoms ($\overline{\mathrm{H}}$). Precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution. We propose to use a new method...
Article
Strongly coupled organic systems are characterized by unusually large Rabi splitting, even in the vacuum state. They show the counter-intuitive feature of a lifetime of the lower polariton state longer than for all other excited states. Here we build up a new theoretical framework to understand the dynamics of such coupled system. In particular, we...
Article
I'll review recent calculations for Casimir interactions between nanostructured surfaces both at thermodynamic equilibrium and out of equilibrium in the framework of the scattering theory. I'll emphasize on the interplay between the thermal Casimir force and the geometry of the surfaces. We predict an enhancement in the heat transfer between metall...
Article
Full-text available
We study quantum reflection of antihydrogen atoms from matter slabs due to the van der Waals/Casimir-Polder (vdW/CP) potential. By taking into account the specificities of antihydrogen and the optical properties and width of the slabs we calculate realistic estimates for the potential and quantum reflection amplitudes. Next we discuss the paradoxic...
Article
Full-text available
We study quantum reflection of antihydrogen atoms from nanoporous media due to the Casimir-Polder (CP) potential. Using a simple effective medium model, we show a dramatic increase of the probability of quantum reflection of antihydrogen atoms if the porosity of the medium increases. We discuss the limiting case of reflections at small energies, wh...
Article
We present detailed calculations for the Casimir force between a plane and a nanostructured surface at finite temperature in the framework of the scattering theory. We then study numerically the effect of finite temperature as a function of the grating parameters and the separation distance. We also infer non-trivial geometrical effects on the Casi...
Article
We study the lateral dependence of the Casimir energy for different corrugated gratings of arbitrary periodic profile. To this end we model the profiles as stacks of horizontal rectangular slices following the profiles' shape and evaluate numerically the Casimir energy between them for different relative lateral displacements of the two corrugated...
Article
Full-text available
We investigate the error made by the pairwise summation (PWS) approximation in three geometries where the exact formula for the Casimir interaction is known: atom-slab, slab-slab and sphere-slab configurations. For each case the interactions are calculated analytically by summing the van der Waals interactions between the two objects. We show that...
Article
Full-text available
Analyzing new experiments with ultracold neutrons (UCNs) we show that physical adsorption of nanoparticles/nano-droplets, levitating in high-excited states in a deep and broad potential well formed by van der Waals/Casimir-Polder (vdW/CP) forces results in new effects on a cross-road of fundamental interactions, neutron, surface and nanoparticle ph...
Article
Full-text available
We present a theoretical study of radiative heat transfer between dielectric nanogratings in the scattering approach. As a comparision with these exact results, we also evaluate the domain of validity of Derjaguin's Proximity Approximation (PA). We consider a system of two corrugated silica plates with various grating geometries, separation distanc...
Article
Full-text available
Physical adsorption of atoms, molecules and clusters on surface is known. It is linked to many phenomena in physics, chemistry, and biology. Usually the studies of adsorption are limited to the particle sizes of up to ~10^2-10^3 atoms. Following a general formalism, we apply it to even larger objects and discover qualitatively new phenomena. A larg...
Article
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....
Article
Full-text available
We compute the radiative heat transfer between nanostructured gold plates in the framework of the scattering theory. We predict an enhancement of the heat transfer as we increase the depth of the corrugations while keeping the distance of closest approach fixed. We interpret this effect in terms of the evolution of plasmonic and guided modes as a f...