- Home

[hal-02129630] Fast quantum control in dissipative systems using dissipationless solutions (5/16/19)

[...]

[hal-02043030] Optimal work in a harmonic trap with bounded stiffness (4/29/19)

We apply Pontryagin's principle to drive rapidly a trapped overdamped Brownian particle in contact with a thermal bath between two equilibrium states corresponding to different trap stiffness $\kappa$. We work out the optimal time dependence $\kappa(t)$ by minimising the work performed on the particle under the non-holonomic constraint $0\leq\kappa\leq\kappa_{\max}$, an experimentally relevant situation. Several important differences arise, as compared with the case of unbounded stiffness that has been analysed in the literature. First, two arbitrary equilibrium states may not always be connected. Second, depending on the operating time $t_{\text{f}}$ and the desired compression ratio $\kappa_{\text{f}}/\kappa_{\text{\i}}$, different types of solutions emerge. Finally, the differences in the minimum value of the work brought about by the bounds may become quite large, which may have a relevant impact on the optimisation of heat engines.

[hal-01987485] Basin Entropy, a Measure of Final State Unpredictability and Its Application to the Chaotic Scattering of Cold Atoms (4/12/19)

[...]

[hal-01945874] Phase transition kinetics for a Bose Einstein condensate in a periodically driven band system (4/12/19)

[...]

[hal-01850268] Engineered Swift Equilibration for Brownian objects: from underdamped to overdamped dynamics (4/29/19)

We propose a general framework to study transformations that drive an underdamped Brownian particle in contact with a thermal bath from an equilibrium state to a new one in an arbitrarily short time. To this end, we make use of a time and space-dependent potential, that plays a dual role: confine the particle, and manipulate the system. In the special case of an isothermal compression or decompression of a harmonically trapped particle, we derive explicit protocols that perform this quick transformation, following an inverse engineering method. We focus on the properties of these protocols, which crucially depend on two key dimensionless numbers that characterize the relative values of the three timescales of the problem, associated with friction, oscillations in the confinement and duration of the protocol. In particular, we show that our protocols encompass the known overdamped version of this problem and extend it to any friction for decompression and to a large range of frictions for compression.

[hal-01787234] Robust calibration of an optical-lattice depth based on a phase shift (4/12/19)

[...]

[hal-01695032] Thermal bath Engineering for Swift Equilibration (4/12/19)

We propose a new protocol that ensures the fast equilibration of an overdamped harmonic oscillator by a joint time-engineering of the confinement strength and of the effective temperature of the thermal bath. We demonstrate experimentally the effectiveness of our protocol with an optically trapped Brownian particle and report an equilibrium recovering time reduced by about two orders of magnitude compared to the natural relaxation time. Our scheme paves the way towards reservoir engineering in nano-systems.

Masques matériels nanométriques Condensat Bose-Einstein Condensation Effet tunnel Tunnel Effect Semiclassical and variationnal approximation Réseaux Optiques Non-adiabatic regime Plasmon polariton de surface Nano-lithography Surface plasmon polariton Jet atomique Optical lattice Bose-Einstein Condensate Atomic beam Bragg scattering Condensation de bose-Einstein Diffraction de Bragg Optique atomique Ultracold atoms Optical molasses Atom chip Mélasse optique Fluorescence microscopy Approximation semi-classique et variationnelle Atom laser Matter wave Lentille de Fresnel Condensat de Bose-Einstein Mirror-magneto-optical trap Espace des phases Bose-Einstein condensate Césium Ouvertures métalliques sub-longueur d'onde Réseau optique Phase space Bose-Einstein Atom optics Rubidium Nano-lithographie Beam splitter Bragg Diffraction Matter waves Sub-wavelength metallic apertures Onde de matière Microscopie de fluorescence Piège magnéto-optique à miroir Atomes froids Transport optimal Periodic potentials Bose Einstein Condensation Supersymmetry in quantum mechanics Cold atoms Fresnel lens Condensats de Bose-Einstein Chaos Optical tweezers Supersymétrie en mécanique quantique Couches mono-moléculaire auto assemblées Étude numérique Puce atomique Self assembled monolayers Bose Einstein condensate Optical lattices Maxwell's demon