arXiv subjects

Pierre Cladé

Publications and source records attributed to Pierre Cladé.

At least 19 recordsLinked to original sources

arXiv2026

Technical Proposal for the Atom Interferometer CERN Experiment (AICE) Facility

We present the technical proposal for the Atom Interferometer CERN Experiment (AICE), a $\mathcal{O}(100)$ m vertical atom interferometer to be installed against the wall of the PX46 access shaft to the LHC. AICE is conceived as a versatile and flexible long-baseline atom-interferometry facility whose primary scientific goal is probing for bosonic ultralight dark matter (ULDM) in a mass range inaccessible to other experiments, with a secondary goal of pioneering the exploration of gravitational waves (GWs) with frequencies in the range ${\sim}$0.03-3 Hz as a pathfinder for future longer-baseline detectors. The initial configuration employs ultracold $^{87}$Sr atoms in a single-photon 698-nm interferometer with three shaft-based atom sources in a multi-source gradiometer geometry, supported by one surface reference source for laser stabilisation and diagnostics, to target scalar ULDM. Operation with $^{88}$Sr will give sensitivity to axion-like particles (ALPs), vector ULDM with $B-L$ couplings and violation of the principle of equivalence, while a $^{171}$Yb upgrade will improve the sensitivity to $B-L$ couplings and equivalence violations. Probing the Einstein equivalence principle (EP) and measuring $α$ will proceed in parallel with the ULDM searches. A conceptual feasibility study and a detailed technical implementation study have established that PX46 is a uniquely mature and implementation-ready site, with no technical showstoppers. Completing site preparation works during LS3 would enable the subsequent installation and operation of AICE without impacting HL-LHC operations. The detector design builds on the VLBAI and MAGIS experiments and the AION-10 Technical Design Report, scaling the strontium gradiometer architecture to the $\sim$100 m baseline. AICE is endorsed by the TVLBAI Proto-Collaboration, comprising 57 institutions in 22 countries.

hep-ex↗

arXiv2025

Image Theory for the Single Bounce Quantum Gravimeter

We develop an image theory for the recently proposed single-bounce quantum gravimeter. Free fall and quantum bounce of a matter wave-packet are described through decompositions over a basis of continuous energies. This leads to a much clearer interpretation of the origin of quantum interferences, associated to semi-classical estimations. We then give new tools to explore the space of parameters, and discuss the expected accuracy of the free-fall acceleration measurement.

quant-ph↗

arXiv2025

Probing the spatial distribution of k-vectors in situ with Bose-Einstein condensates

We present a novel method for mapping \textit{in situ} the spatial distribution of photon momentum across a laser beam using a Bose-Einstein condensate (BEC) as a moving probe. By displacing the BEC, we measure the photon recoil by atom interferometry at different positions in the laser beam and thus reconstruct a two-dimensional map of the local intensity and effective dispersion of the $k$ wave vector. Applied to a beam diffracted by a diaphragm, this method reveals a local \textit{extra recoil} effect, which exceeds the magnitude $hν/c$ of the individual plane-waves over which the beam can be decomposed. This method offers a new way to precisely characterize wavefront distortions and to evaluate one of the major systematic bias sources in quantum sensors based on atom interferometry.

physics.atom-ph↗

arXiv2025

Single-bounce quantum gravimeter to measure the free-fall of anti-hydrogen

We propose an innovative concept for a quantum gravimeter, where atoms prepared in a Heisenberg-limited state perform a single bounce on a mirror followed by a free fall. This quantum gravimeter produces a simple and robust interference pattern which should allow to measure the free-fall acceleration of atoms. We estimate the expected accuracy of the measurement in the GBAR experiment, which aims at testing the equivalence principle on anti-hydrogen at CERN antimatter facilities. Using simulations and estimation techniques based on Cramer-Rao law and Fisher information, we show that the new quantum sensor improves the expected accuracy of the measurement. The proposal opens the door to free fall measurements on rare or exotic atomic species, especially in situations where experimental time or detection events are limited by intrinsic physical reasons.

quant-ph↗

arXiv2025

Letter of Intent: AICE -- 100m Atom Interferometer Experiment at CERN

We propose an O(100)m Atom Interferometer (AI) experiment -- AICE -- to be installed against a wall of the PX46 access shaft to the LHC. This experiment would probe unexplored ranges of the possible couplings of bosonic ultralight dark matter (ULDM) to atomic constituents and undertake a pioneering search for gravitational waves (GWs) at frequencies intermediate between those to which existing and planned experiments are sensitive, among other fundamental physics studies. A conceptual feasibility study showed that this AI experiment could be isolated from the LHC by installing a shielding wall in the TX46 gallery, and surveyed issues related to the proximity of the LHC machine, finding no technical obstacles. A detailed technical implementation study has shown that the preparatory civil-engineering work, installation of bespoke radiation shielding, deployment of access-control systems and safety alarms, and installation of an elevator platform could be carried out during LS3, allowing installation and operation of the AICE detector to proceed during Run 4 without impacting HL-LHC operation. These studies have established that PX46 is a uniquely promising location for an AI experiment. We foresee that, if the CERN management encourages this Letter of Intent, a significant fraction of the Terrestrial Very Long Baseline Atom Interferometer (TVLBAI) Proto-Collaboration may wish to contribute to AICE.

hep-ex↗

arXiv2022

An atom interferometer driven by a picosecond frequency comb

We demonstrate a light-pulse atom interferometer based on the diffraction of free-falling atoms by a picosecond frequency-comb laser. More specifically, we coherently split and recombine wave packets of cold $^{87}$Rb atoms by driving stimulated Raman transitions between the $|5s~^2S_{1/2},F=1\rangle$ and $|5s~^2S_{1/2},F=2\rangle$ hyperfine states, using two trains of picosecond pulses in a counter-propagating geometry. We study the impact of the pulses length as well as of the interrogation time onto the contrast of the atom interferometer. Our experimental data are well reproduced by a numerical simulation based on an effective coupling which depends on the overlap between the pulses and the atomic cloud. These results pave the way for extending light-pulse interferometry to transitions in other spectral regions and therefore to other species, for new possibilities in metrology, sensing of gravito-inertial effects and tests of fundamental physics.

physics.atom-ph↗

arXiv2022

Quantum interference measurement of the free fall of anti-hydrogen

We analyze a quantum measurement designed to improve the accuracy for the free-fall acceleration of anti-hydrogen in the GBAR experiment. Including the effect of photo-detachment recoil in the analysis and developing a full quantum analysis of anti-matter wave propagation, we show that the accuracy is improved by approximately three orders of magnitude with respect to the classical timing technique planned for the current experiment.

quant-ph↗

arXiv2021

Improving the statistical analysis of anti-hydrogen free fall by using near edge events

An accurate evaluation of the gravity acceleration from the timing of free fall of anti-hydrogen atoms in the GBAR experiment requires to account for obstacles surrounding the anti-matter source. These obstacles reduce the number of useful events but may improve accuracy since the edges of the shadow of obstacles on the detection chamber depends on gravity, bringing additional information on the value of $g$. We perform Monte Carlo simulations to obtain the dispersion and give a qualitative understanding of the results by analysing the statistics of events close to an edge. We also study the effect of specular quantum reflections of anti-hydrogen on surfaces and show that they do not degrade the accuracy that much.

physics.atom-ph↗

arXiv2021

Analysis of the timing of freely falling antihydrogen

We evaluate the accuracy to be expected for the measurement of free fall acceleration of antihydrogen in the GBAR experiment, accounting for the recoil transferred in the photodetachment process. We show that the uncertainty on the measurement of gravity comes mainly from the initial velocity dispersion in the ion trap so that the photodetachment recoil is not the limiting factor to the precision as a naive analysis would suggest. This result will ease the constraints on the choice of the photodetachment laser parameters.

physics.atom-ph↗

arXiv2020

Velocity-dependent phase shift in a light-pulse atom interferometer

Atom interferometry relies on the separation and recombination of atom wavepackets. When the two paths overlap perfectly at the end of the interferometer, the phase is insensitive to the atomic velocity distribution. Here, we show that, when the separation and recombination is performed using a Raman transition there is a displacement of the atomic wavepacket due to a phase shift during light pulses. Because of the variation of the laser intensity seen by the atoms, there is an imperfect cancellation of these displacements. The observation of a velocity-dependent phase shift on the interferometer is the signature of this effect, which has been modeled. Thanks to the signature we have identified, we are able to compensate for this effect by applying laser power ramps during the interferometer to mitigate intensity variations.

physics.atom-ph↗

arXiv2019

State of the art in the determination of the fine structure constant and the ratio $h/m_\mathrm{u}$

The fine structure constant $α$ and the ratio $h/m_{\mathrm{u}}$ between the Planck constant and the unified atomic mass are keystone constants for the determination of other fundamental physical constants, especially the ones involved in the framework of the future International System of units. This paper presents how these two constants, which can be deduced from one another, are measured. We will present in detail the measurement of $h/m_\mathrm{Rb}$ performed by atomic interferometry at the Laboratoire Kastler Brossel in Paris. This type of measurement also allows a test of the standard model to be carried out with unparalleled accuracy.

physics.atom-ph↗

arXiv2018

Observation of Extra Photon Recoil in a Distorted Optical Field

Light carries momentum which induces on atoms a recoil for each photon absorbed. In vacuum, for a monochromatic beam of frequency $ν$, the global momentum per photon is bounded by general principles and is smaller than $h ν/c$ leading to a limit on the recoil. However, locally this limit can be broken. In this paper, we give a general formula to calculate the recoil in vacuum. We show that in a laser beam with a distorted optical field, there are regions where the recoil can be higher than this limit. Using atoms placed in those regions we are able to measure directly the extra recoil.

physics.atom-ph↗

arXiv2014

Bloch oscillations in atom interferometry

In Paris, we are using an atom interferometer to precisely measure the recoil velocity of an atom that absorbs a photon. In order to reach a high sensitivity, many recoils are transferred to atoms using the Bloch oscillations technique. In this lecture, I will present in details this technique and its application to high precision measurement. I will especially describe in details how this method allows us to perform an atom recoil measurement at the level of $1.3 \times 10^{-9}$. This measurement is used in the most precise determination of the fine structure constant that is independent of quantum electrodynamics.

physics.atom-ph↗

arXiv2013

State of the art in the determination of the fine structure constant: test of Quantum Electrodynamics and determination of h/mu

The fine structure constant $α$ has a particular status in physics. Its precise determination is required to test the quantum electrodynamics (QED) theory. The constant $α$ is also a keystone for the determination of other fundamental physical constants, especially the ones involved in the framework of the future International System of units. This paper presents Paris experiment, where the fine structure constant is determined by measuring the recoil velocity of a rubidium atom when it absorbs a photon. The impact of the recent improvement of QED calculations of the electron moment anomaly and the recent measurement of the cesium atom recoil at Berkeley will be discussed. The opportunity to provide a precise value of the ratio $h/m_{\mathrm{u}}$ between the Planck constant and the atomic mass constant will be investigated.

quant-ph↗

arXiv2013

Compact atomic gravimeter based on a pulsed and accelerated optical lattice

We present a new scheme of compact atomic gravimeter based on atom interferometry. Atoms are maintained against gravity using a sequence of coherent accelerations performed by the Bloch oscillations technique. We demonstrate a sensitivity of 4.8$\times 10^{-8}$ with an integration time of 4 min. Combining this method with an atomic elevator allows to measure the local gravity at different positions in the vacuum chamber. This method can be of relevance to improve the measurement of the Newtonian gravitational constant $G$.

physics.atom-ph↗

arXiv2010

New determination of the fine structure constant and test of the quantum electrodynamics

We report a new measurement of the ratio $h/m_{\mathrm{Rb}}$ between the Planck constant and the mass of $^{87}\mathrm{Rb}$ atom. A new value of the fine structure constant is deduced, $α^{-1}=137.035\,999\,037\,(91)$ with a relative uncertainty of $6.6\times 10^{-10}$. Using this determination, we obtain a theoretical value of the electron anomaly $a_\mathrm{e}=0.001~159~652~181~13(84)$ which is in agreement with the experimental measurement of Gabrielse ($a_\mathrm{e}=0.001~159~652~180~73(28)$). The comparison of these values provides the most stringent test of the QED. Moreover, the precision is large enough to verify for the first time the muonic and hadronic contributions to this anomaly.

physics.atom-ph↗

arXiv2010

Theoretical Analysis of a Large Momentum Beamsplitter using Bloch Oscillations

In this paper, we present the implementation of Bloch oscillations in an atomic interferometer to increase the separation of the two interfering paths. A numerical model, in very good agreement with the experiment, is developed. The contrast of the interferometer and its sensitivity to phase fluctuations and to intensity fluctuations are also calculated. We demonstrate that the sensitivity to phase fluctuations can be significantly reduced by using a suitable arrangement of Bloch oscillations pulses.

physics.atom-ph↗

arXiv2009

Large Momentum Beamsplitter using Bloch Oscillations

The sensitivity of an inertial sensor based on an atomic interfermometer is proportional to the velocity separation of atoms in the two arms of the interferometer. In this paper we describe how Bloch oscillations can be used to increase this separation and to create a large momentum transfer (LMT) beamsplitter. We experimentally demonstrate a separation of 10 recoil velocities. Light shifts during the acceleration introduce phase fluctuations which can reduce the contrast of the interferometer. We precisely calculate this effect and demonstrate that it can be significantly reduced by using a suitable combination of LMT pulses. We finally show that this method seems to be very promising to realize LMT beamsplitter with several 10s of recoil and a very good efficiency.

physics.atom-ph↗