We study experimentally, numerically and theoretically the optimal mean time needed by a Brownian... more We study experimentally, numerically and theoretically the optimal mean time needed by a Brownian particle, freely diffusing either in one or two dimensions, to reach, within a tolerance radius Rtol , a target at a distance L from an initial position in the presence of resetting. The reset position is Gaussian distributed with width σ . We derived and tested two resetting protocols, one with a periodic and one with random (Poissonian) resetting times. We computed and measured the full first-passage probability distribution that displays spectacular spikes immediately after each resetting time for close targets. We study the optimal mean first-passage time as a function of the resetting period/rate for different target distances (values of the ratios b = L/σ ) and target size (a = Rtol/L). We find an interesting phase transition at a critical value of b, both in one and two dimensions. The details of the calculations as well as experimental setup and limitations are discussed.
We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging... more We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel, are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath. We derive, from a simple model, an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging... more We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel, are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath. We derive, from a simple model, an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Engineered swift equilibration of a Brownian particle Ignacio Martinez, Artyom Petrosyan, David Guéry-Odelin, Emmanuel Trizac, Sergio Ciliberto
Journal of Statistical Mechanics: Theory and Experiment, 2016
We experimentally study the statistical properties of the energy fluxes in two systems whose comp... more We experimentally study the statistical properties of the energy fluxes in two systems whose components are kept at different temperatures. The first system under consideration is an electric circuit which is composed by two resistances, kept at different temperatures and connected by a capacitance (conservative coupling) which couples the thermal noise of the two resistances. The other system is composed by two Brownian particles, trapped with optical tweezers, interacting through a dissipative hydrodynamic coupling. The particles are subjected to an effective temperature difference obtained by random forcing the position of one trap. In these two systems we measure the properties of the energy flowing between the two reservoirs. The role on these properties of the coupling and of the method used to produce the highest temperature is analyzed.
We measure the fluctuations of the position of a silica bead trapped by an optical tweezers durin... more We measure the fluctuations of the position of a silica bead trapped by an optical tweezers during the aging of a Laponite suspension. We find that the effective temperature is equal to the bath temperature.
In this paper we report a new method for determining the critical threshold of the Fr\'eederi... more In this paper we report a new method for determining the critical threshold of the Fr\'eedericksz transition driven by an electric field. It is based on the measurement of the amplitude of the molecule fluctuations as a function of the voltage difference applied to a planar nematic cell. The precise measurement of the director fluctuations of the liquid crystal is made possible by the use of a very precise and sensitive polarization interferometer. The great advantage of the method is that it does not depend on complex fits as it is usually done in literature.
In a planar aligned photorefractive liquid crystal light valve we show the appearance of optical ... more In a planar aligned photorefractive liquid crystal light valve we show the appearance of optical structures induced by a single mirror feedback. We report the typical responses of the valve as a function of the pump intensity. We observe that the length scale of the structures scales with the light free propagation length, according with a diffractive feedback model.
... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Labora... more ... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Laboratoire de Physique Petrosyan, Artyom; ENSL, Laboratoire de Physique Ciliberto, Sergio; ENSL, Laboratoire de Physique Keywords: ageing, colloids, rheology, statistical physics ...
We show that a very large optical response is obtained in azo-dye doped nematic liquid crystals f... more We show that a very large optical response is obtained in azo-dye doped nematic liquid crystals for low input light intensities (of the order of a few tens of muW/cm2 and that this extreme sensitivity of the nematic film results from a combined action of the photoisomerization process of the azo-dye molecules and the light-induced changes of the anchoring energy. The liquid crystal reorientation can be controlled by changing the molecular length of the ionic surfactant which is used as anchoring agent.
We study experimentally, numerically and theoretically the optimal mean time needed by a Brownian... more We study experimentally, numerically and theoretically the optimal mean time needed by a Brownian particle, freely diffusing either in one or two dimensions, to reach, within a tolerance radius Rtol , a target at a distance L from an initial position in the presence of resetting. The reset position is Gaussian distributed with width σ . We derived and tested two resetting protocols, one with a periodic and one with random (Poissonian) resetting times. We computed and measured the full first-passage probability distribution that displays spectacular spikes immediately after each resetting time for close targets. We study the optimal mean first-passage time as a function of the resetting period/rate for different target distances (values of the ratios b = L/σ ) and target size (a = Rtol/L). We find an interesting phase transition at a critical value of b, both in one and two dimensions. The details of the calculations as well as experimental setup and limitations are discussed.
We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging... more We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel, are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath. We derive, from a simple model, an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging... more We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel, are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath. We derive, from a simple model, an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Engineered swift equilibration of a Brownian particle Ignacio Martinez, Artyom Petrosyan, David Guéry-Odelin, Emmanuel Trizac, Sergio Ciliberto
Journal of Statistical Mechanics: Theory and Experiment, 2016
We experimentally study the statistical properties of the energy fluxes in two systems whose comp... more We experimentally study the statistical properties of the energy fluxes in two systems whose components are kept at different temperatures. The first system under consideration is an electric circuit which is composed by two resistances, kept at different temperatures and connected by a capacitance (conservative coupling) which couples the thermal noise of the two resistances. The other system is composed by two Brownian particles, trapped with optical tweezers, interacting through a dissipative hydrodynamic coupling. The particles are subjected to an effective temperature difference obtained by random forcing the position of one trap. In these two systems we measure the properties of the energy flowing between the two reservoirs. The role on these properties of the coupling and of the method used to produce the highest temperature is analyzed.
We measure the fluctuations of the position of a silica bead trapped by an optical tweezers durin... more We measure the fluctuations of the position of a silica bead trapped by an optical tweezers during the aging of a Laponite suspension. We find that the effective temperature is equal to the bath temperature.
In this paper we report a new method for determining the critical threshold of the Fr\'eederi... more In this paper we report a new method for determining the critical threshold of the Fr\'eedericksz transition driven by an electric field. It is based on the measurement of the amplitude of the molecule fluctuations as a function of the voltage difference applied to a planar nematic cell. The precise measurement of the director fluctuations of the liquid crystal is made possible by the use of a very precise and sensitive polarization interferometer. The great advantage of the method is that it does not depend on complex fits as it is usually done in literature.
In a planar aligned photorefractive liquid crystal light valve we show the appearance of optical ... more In a planar aligned photorefractive liquid crystal light valve we show the appearance of optical structures induced by a single mirror feedback. We report the typical responses of the valve as a function of the pump intensity. We observe that the length scale of the structures scales with the light free propagation length, according with a diffractive feedback model.
... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Labora... more ... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Laboratoire de Physique Petrosyan, Artyom; ENSL, Laboratoire de Physique Ciliberto, Sergio; ENSL, Laboratoire de Physique Keywords: ageing, colloids, rheology, statistical physics ...
We show that a very large optical response is obtained in azo-dye doped nematic liquid crystals f... more We show that a very large optical response is obtained in azo-dye doped nematic liquid crystals for low input light intensities (of the order of a few tens of muW/cm2 and that this extreme sensitivity of the nematic film results from a combined action of the photoisomerization process of the azo-dye molecules and the light-induced changes of the anchoring energy. The liquid crystal reorientation can be controlled by changing the molecular length of the ionic surfactant which is used as anchoring agent.
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