A5102721645- Advanced Frequency and Time Standards
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Force Microscopy Techniques and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Quantum Mechanics and Applications
- Relativity and Gravitational Theory
- Noncommutative and Quantum Gravity Theories
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Radioactive Decay and Measurement Techniques
- Scientific Measurement and Uncertainty Evaluation
- Advanced Fiber Laser Technologies
- Near-Field Optical Microscopy
- Black Holes and Theoretical Physics
- Semiconductor Lasers and Optical Devices
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Pulsars and Gravitational Waves Research
- Geophysics and Sensor Technology
- Physics of Superconductivity and Magnetism
- Experimental and Theoretical Physics Studies
- GNSS positioning and interference
- Organic and Molecular Conductors Research
Systèmes de Référence Temps-Espace
2016-2025
Bruker (United States)
2016-2025
Medical University of Graz
2025
Centre National de la Recherche Scientifique
2015-2024
Sorbonne Université
2015-2024
Université Paris Sciences et Lettres
2015-2024
Observatoire de Paris
2012-2024
Bruker (China)
2022
Bureau international des poids et mesures
2000-2021
Royal Observatory of Belgium
2021
We use 6 yrs of accurate hyperfine frequency comparison data the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such field can induce harmonic variations fine structure constant, mass fermions, quantum chromodynamic scale, which will directly impact rubidium/caesium transition ratio. find no signal consistent with candidate but provide improved constraints on coupling putative standard matter. Our limits are complementary...
We report on a new test of the gravitational redshift and thus local position invariance, an integral part Einstein equivalence principle, which is foundation general relativity all metric theories gravitation. use data spanning 1008 days from two satellites Galileo, Europe's global satellite navigation system, were launched in 2014, but accidentally delivered elliptic rather than circular orbits. The resulting modulation onboard atomic clocks allows determination with high accuracy....
We discuss the IAU resolutions B1.3, B1.4, B1.5, and B1.9 that were adopted during 24th General Assembly in Manchester, 2000, provides details on explanations for these resolutions. It is explained why they present significant progress over corresponding 1991 are necessary light of accuracies astrometry, celestial mechanics, metrology. In fact, most consistent with astronomical models software already use. The metric tensors gravitational potentials both Barycentric Celestial Reference...
This paper describes advances in microwave frequency standards using laser-cooled atoms at BNM-SYRTE. First, recent improvements of the $^{133}$Cs and $^{87}$Rb atomic fountains are described. Thanks to routine use a cryogenic sapphire oscillator as an ultra-stable local reference, fountain instability $1.6\times 10^{-14}\tau^{-1/2}$ where $\tau $ is measurement time seconds measured. The second advance powerful method control shift due cold collisions. These two lead stability $2\times...
We report on a new experiment that tests for violation of Lorentz invariance (LI), by searching dependence atomic transition frequencies the orientation spin involved states (Hughes-Drever type experiment). The are measured using laser cooled $^{133}\mathrm{Cs}$ fountain clock, operating particular combination Zeeman substates. analyze results within framework violating standard model extension (SME), where our is sensitive to largely unexplored region SME parameter space, corresponding...
In this paper, we study the local observational consequences of a violation Einstein equivalence principle induced by models light scalar dark matter (DM). We focus on two different where field couples linearly or quadratically to standard model fields. For both these cases, derive solutions field. also from first principles expressions for types observables: (i) comparison atomic sensors that are differently sensitive constants nature, and (ii) differential acceleration between test masses...
We report on the first earth-scale quantum sensor network based optical atomic clocks aimed at dark matter (DM) detection. Exploiting differences in susceptibilities to fine-structure constant of essential parts an clock, i.e. cold atoms and reference cavity, we can perform sensitive searches for signatures without need real-time comparisons clocks. a two orders magnitude improvement constraints transient variations constant, which considerably improves detection limit standard model (SM) -...
We search for transient variations of the fine structure constant using data from a European network fiber-linked optical atomic clocks. By searching coherent in recorded clock frequency comparisons across network, we significantly improve constraints on constant. For example, constrain variation alpha to <5*10^-17 transients duration 10^3 s. This analysis also presents possibility dark matter, mysterious substance hypothesised explain galaxy dynamics and other astrophysical phenomena that...
The space-time explorer and quantum equivalence principle space test (STE-QUEST) recently proposed, aims at performing a precision of the weak (WEP), fundamental cornerstone general relativity. Taking advantage ideal operation conditions for high-precision sensing on board satellite, it to detect possible violations WEP down ${10}^{\ensuremath{-}17}$ level. This level performance leads stringent environmental requirements control spacecraft. We assume an dual-species atom interferometer...
Abstract We propose a simple modification of space-based gravitational wave (GW) detector optical benches which would enable the measurement vacuum birefringence light induced by axion dark matter through its coupling to electromagnetism. Specifically, we change half-wave plate circular polarizer. While marginally affecting sensitivity GW factor $\sqrt{2}$, show that such an adjustment make future detectors as LISA, TianQin, Taiji and Big-Bang Observer most sensitive experiments at low masses.
An overview of the existing two-dimensional carrier profiling tools using scanning probe microscopy includes several tunneling modes, capacitance microscopy, Kelvin spreading resistance and dopant selective etching. The techniques are discussed compared in terms sensitivity or concentration range which can be covered, quantification possibility, final resolution, is influenced by intrinsic imaging resolution as well response investigated property to gradients sampling volume. From this...
We report observations of the ferroelectric domain structure in epitaxial lead zirconate titanate (PbZr0.2Ti0.8O3) thin films using piezoresponse microscopy. By manipulating film thickness, a uniform two-dimensional grid 90° domains (a domains, i.e., c axis plane film) has been induced. Our studies show that out polarization direction is preferentially oriented. have observed as regions low piezoresponse, compared to fully oriented regions. studied influence these and walls on nucleation...
The frequencies of a cryogenic sapphire oscillator and hydrogen maser are compared to set new constraints on possible violation Lorentz invariance. We determine the variation frequency as function its orientation (Michelson-Morley test) velocity (Kennedy-Thorndike with respect preferred frame candidate. constrain corresponding parameters Mansouri Sexl test theory delta-beta + 1/2 = (1.5+/-4.2) x 10(-9) beta-alpha - 1= (-3.1+/-6.9) 10(-7) which is same order best previous result for former...
We report relativity tests based on data from two simultaneous Michelson-Morley experiments, spanning a period of more than 1 yr. Both were actively rotated turntables. One (in Berlin, Germany) uses optical Fabry-Perot resonators made fused silica; the other Perth, Australia) microwave whispering-gallery sapphire resonators. Within standard model extension, we obtain limits Lorentz violation for electrons (5 coefficients) and photons (8) at levels down to ${10}^{\ensuremath{-}16}$, improved...
We present the first results from a rotating Michelson-Morley experiment that uses two orthogonally orientated cryogenic sapphire resonator oscillators operating in whispering gallery modes near 10 GHz. The is used to test for violations of Lorentz invariance framework photon sector standard model extension (SME), as well isotropy term Robertson-Mansouri-Sexl (RMS) framework. In SME we set new bound on previously unmeasured kappa(ZZ)(e-) component 2.1(5.7) x 10(-14), and more stringent...
Atom interferometers allow the measurement of acceleration freely falling atoms with respect to an experimental platform at rest on Earth's surface.Such experiments have been used test universality free fall by comparing that a classical object.In recent paper, Müller, Peters and Chu [A precision gravitational redshift interference matter waves, Nature 463, 926-929 (2010)] argued atom also provide very accurate (or clock rates).Considering as operating Compton frequency associated mass, they...
We describe the realization of a 5 km free-space coherent optical link through turbulent atmosphere between telescope and ground target. present phase noise link, limited mainly by atmospheric turbulence mechanical vibrations discuss implications our results for applications, with particular emphasis on Doppler ranging to satellites long-distance frequency transfer.
Bidirectional ground-satellite laser links suffer from turbulence-induced scintillation and phase distortion. We study the impact of turbulence on coherent detection related noise that restricts time frequency transfer precision. evaluate capacity to obtain a two-way cancellation atmospheric effects despite asymmetry between up- downlink limits link reciprocity. For links, is induced by point-ahead angle possibly use, for ground terminal, different transceiver diameters, in reception...
The Einstein Equivalence Principle (EEP) is one of the foundations theory General Relativity and several alternative theories gravitation predict violations EEP. Experimental constraints on this fundamental principle nature are therefore paramount importance. EEP can be split into three sub-principles: universality free fall (UFF), local Lorentz invariance (LLI) position (LPI). In paper we propose to use stable clocks in eccentric orbits perform a test gravitational redshift, consequence...
We propose a new type of experiment that compares the frequency clock (an ultrastable optical cavity in this case) at time $t$ to its own some $t\text{\ensuremath{-}}T$ earlier, by ``storing'' output signal (photons) fiber delay line. In ultralight oscillating dark matter (DM) models, such an is sensitive coupling DM standard model fields, through oscillations and lengths refractive index. Additionally, sensitivity significantly enhanced around mechanical resonances cavity. present...
A conductive atomic force microscope (AFM) tip based on B-implanted diamond has been developed for the determination of spatial distribution charge carriers in semiconducting structures. The characteristics this have determined by studying current–voltage behavior as a function substrate resistivity and load. From work model electrical properties microcontact is emerging. It includes an Ohmic contribution to overall resistance, which related plastically deformed area, contributions from...