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Procédé de mesure de la force d’interaction entre une portion et une pointe d’une sonde de force d’un AFM solidaire d’un moyen d’excitation, le moyen d’excitation étant apte à vibrer en fonction d’un signal d’excitation e(t), le procédé comprenant une étape de mise en excitation de la sonde de force, un signal d’excitation étant appliqué configuré pour engendrer, une déflexion libre s0(t) formant un signal sinusoïdal modulé en amplitude par une impulsion, la sonde de force entrant en résonance à une fréquence de résonance libre f_0, une étape de mesure de la déflexion s(t), la sonde de force entrant en résonance à une fréquence de résonance d’interaction f_T, une étape de traitement dans laquelle est évalué un décalage fréquentiel Δf_T, différence entre la fréquence de résonance d’interaction de la sonde de force, et la fréquence de résonance libre.

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The effective control of atomic coherence with cold atoms has made atom interferometry an essential tool for quantum sensors and precision measurements. The performance of these interferometers is closely related to the operation of large wave packet separations. We present here a novel approach for atomic beam splitters based on the stroboscopic stabilization of quantum states in an accelerated optical lattice. The corresponding Floquet state is generated by optimal control protocols. In this way, we demonstrate an unprecedented Large Momentum Transfer (LMT) interferometer, with a momentum separation of 600 photon recoils ($600\hbar k$) between its two arms. Each LMT beam splitter is realized in a remarkably short time (2 ms) and is highly robust against the initial velocity dispersion of the wave packet and lattice depth fluctuations. Our study shows that Floquet engineering is a promising tool for exploring new frontiers in quantum physics at large scales, with applications in quantum sensing and testing fundamental physics.

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We numerically study the optimal control of an atomic Bose-Einstein condensate in an optical lattice. We present two generalizations of the gradient-based algorithm, GRAPE, in the non-linear case and for a two-dimensional lattice. We show how to construct such algorithms from Pontryagin’s maximum principle. A wide variety of target states can be achieved with high precision by varying only the laser phases setting the lattice position. We discuss the physical relevance of the different results and the future directions of this work.

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Microscopically probing quantum many-body systems by resolving their constituent particles is essential for understanding quantum matter. In most physical systems, distinguishing individual particles, such as electrons in solids, or neutrons and quarks in neutron stars, is impossible. Atombased quantum simulators offer a unique platform that enables the imaging of each particle in a many-body system. Until now, however, this capability has been limited to quantum systems in discretized space such as optical lattices and tweezers, where spatial degrees of freedom are quantized. Here, we introduce a novel method for imaging atomic quantum many-body systems in the continuum, allowing for in situ resolution of every particle. We demonstrate the capabilities of our approach on a two-dimensional atomic Fermi gas. We probe the density correlation functions, resolving their full spatial functional form, and reveal the shape of the Fermi hole arising from Pauli exclusion as a function of temperature. Our method opens the door to probing strongly-correlated quantum gases in the continuum with unprecedented spatial resolution, providing in situ access to spatially resolved correlation functions of arbitrarily high order across the entire system.

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In the absence of external forcing, all trajectories on the phase plane of the van der Pol oscillator tend to a closed, periodic, trajectory -- the limit cycle -- after infinite time. Here, we drive the van der Pol oscillator with an external time-dependent force to reach the limit cycle in a given finite time. Specifically, we are interested in minimising the non-conservative contribution to the work when driving the system from a given initial point on the phase plane to any final point belonging to the limit cycle. There appears a speed limit inequality, which expresses a trade-off between the connection time and cost -- in terms of the non-conservative work. We show how the above results can be { generalized to the broader family of non-linear oscillators given by} the Liénard equation. Finally, we also look into the problem of minimising the total work done by the external force.

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Sujets

Espace des phases Chaos-assisted tunneling Condensats de Bose– Einstein Optical lattices Hamiltonian Engineering Plasmon polariton de surface Bose-Einstein Approximation semi-classique et variationnelle Quantum chaos Fluorescence microscopy Atom chip Bose–Einstein condensates Gaz quantiques Optique atomique Optimal control theory Césium Condensat de Bose-Einstein Numerical methods Réseau optique Fluid Dimension Atom laser Gaz quantique Lattice Bose Einstein condensate Bose-Einstein Condensates Piège magnéto-optique à miroir Lentille de Fresnel Contrôle optimal Chaos quantique Quantum Quantum collisions Experimental results Atomic beam Optical lattice Floquet theory Réseaux optiques Mélasse optique Chaos Collisions ultrafroides Bose-Einstein condensates Effet rochet Fresnel lens Phase space Dynamical tunneling Ouvertures métalliques sub-longueur d'onde Electromagnetic field Condensation Puce atomique Field equations stochastic Effet tunnel assisté par le chaos Atomes froids Atom optics Quantum optimal control Couches mono-moléculaire auto assemblées Optical molasses Matter waves Bose-Einstein Condensate Diffraction de Bragg Ultracold atoms Jet atomique Masques matériels nanométriques Cold atoms Condensat Bose-Einstein Physique quantique Atomes ultrafroids dans un réseau optique Mechanics Mirror-magneto-optical trap Maxwell's demon Contrôle optimal quantique Condensats de Bose Einstein Current Non-adiabatic regime Nano-lithographie Constraint Onde de matière Initial state Entropy production Beam splitter Condensation de bose-Einstein Matter wave Théorie de Floquet Effet tunnel dynamique Microscopie de fluorescence Periodic potentials Quantum control Bose-Einstein condensate Bose-Einstein condensates Coherent control Cold atoms and matter waves Cold gases in optical lattices Optical tweezers Nano-lithography Optical Time dependence Bragg Diffraction Bose Einstein Condensation Bragg scattering Condensats de Bose-Einstein Levitodynamics Effet tunnel

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82