We present an experiment in which a one-bit memory is constructed, using a system of a single colloidal particle trapped in a modulated double-well potential. We measure the amount of heat dissipated to erase a bit and we establish that in the limit
of long erasure cycles the mean dissipated heat saturates at the Landauer bound, i.e. the minimal quantity of heat necessarily produced to delete a classical bit of information. This result demonstrates the intimate link between information theory and thermodynamics. To stress this connection we also show that a detailed Jarzynski equality is verified, retrieving the Landauers bound independently of the work done on the system. The experimental details are presented and the experimental errors carefully discussed
We report here the observation of a surprising phenomenon consisting in a oscillating phase transition which appears in a binary mixture, PMMA/3-octanone, when this is enlightened by a strongly focused infrared laser beam. PMMA/3-octanone has a UCST
(Upper Critical Solution Temperature) which presents a critical point at temperature Tc = 306.6 K and volume fraction $phi$c = 12.8 % [Crauste et al., ArXiv 1310.6720, 2012]. This oscillatory phenomenon appears because of thermophoretic and electrostriction effects and non-linear diffusion. We analyze these oscillations and we propose a simple model which includes the minimal ingredients to produce the oscillatory behavior. Phase transitions in binary mixtures are still a widely studied subject, specifically near the critical point where several interesting and not completely understood phenomena may appear, among them we recall the critical Casimir forces [2],[3], confinement effects [4], [5] and out-of-equilibrium dynamics after a quench. The perturbation of the binary mixtures by mean of external fields is also an important and recent field of investigation [6]. For example, a laser can induce interesting phenomena in demixing binary mixtures because the radiation pressure can deform the interface between the two phases and it can be used to measure the interface tension [7]. Depending on the nature of the binary mixtures, laser illumination can also lead to a mixing or demixing transition. In ref.[8], focused infrared laser light heats the medium initially in the homogeneous phase and causes a separation in the LCST (Low Critical Solution Temperature) system. The radiation pressure gradients in a laser beam also contribute in the aggregation of polymers , thus producing a phase transition. The local heating may induce thermophoretic forces which attract towards the laser beam one of the binary-mixture components [9]. Other forces like electrostriction can also be involved [10]. In this letter, we report a new phenomenon, which consists in an oscillating phase transition induced by a constant illumination from an infrared laser beam in the heterogeneous region of an UCST (Upper Critical Solution Temperature) binary mixture. Oscillation phenomena in phase transition have already been reported in slow cooling UCST [11],[12] but as far as we know, never induced by a stationary laser illumination. After describing our experimental setup , we will present the results. Then we will use a very simplified model which contains the main necessary physical ingredients to induce this oscillation phenomenon.
In this paper we report a new method for determining the critical threshold of the Freedericksz 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 differen
ce 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.
We report experimental and numerical evidences that the dynamics of the director of a liquid crystal driven by an electric field close to the critical point of the Freedericksz Transition(FT) is not described by a Landau-Ginzburg (LG) equation as it
is usually done in literature. The reasons are related to the very crude approximations done to obtain this equation, to the finite value of the anchoring energy and to small asymmetries on boundary conditions. We also discuss the difference between the use of LG equation for the statics and the dynamics. These results are useful in all cases where FT is used as an example for other orientational transitions.
A single bit memory system is made with a brownian particle held by an optical tweezer in a double-well potential and the work necessary to erase the memory is measured. We show that the minimum of this work is close to the Landauers bound only for v
ery slow erasure procedure. Instead a detailed Jarzynski equality allows us to retrieve the Landauers bound independently on the speed of this erasure procedure. For the two separated subprocesses, i.e. the transition from state 1 to state 0 and the transition from state 0 to state 0, the Jarzynski equality does not hold but the generalized version links the work done on the system to the probability that it returns to its initial state under the time-reversed procedure.
We study the effects of the finite number of experimental data on the computation of a generalized fluctuation-dissipation relation around a nonequilibrium steady state of a Brownian particle in a toroidal optical trap. We show that the finite sampli
ng has two different effects, which can give rise to a poor estimate of the linear response function. The first concerns the accessibility of the generalized fluctuation-dissipation relation due to the finite number of actual perturbations imposed to the control parameter. The second concerns the propagation of the error made at the initial sampling of the external perturbation of the system. This can be highly enhanced by introducing an estimator which corrects the error of the initial sampled condition. When these two effects are taken into account in the data analysis, the generalized fluctuation-dissipation relation is verified experimentally.
The orientation fluctuations of the director of a liquid crystal are measured, by a sensitive polarization interferometer, close to the Freedericksz transition, which is a second order transition driven by an electric field. We show that near the cri
tical value of the field the spatially averaged order parameter has a generalized Gumbel distribution instead of a Gaussian one. The latter is recovered away from the critical point. The relevance of slow modes is pointed out. The parameter of generalized Gumbel is related to the effective number of degrees of freedom.
