Bernard Gaveau

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Stochastic dynamics is generated by a matrix of transition probabilities. Certain eigenvectors of this matrix provide observables, and when these are plotted in the appropriate multidimensional space the phases (in the sense of phase transitions) of the underlying system become manifest as extremal points. This geometrical construction, which we call an(More)
We propose a novel definition of efficiency, valid for motors in a nonequilibrium stationary state exchanging heat and possibly other resources with an arbitrary number of reservoirs. This definition, based on a rational estimation of all irreversible effects associated with power production, is adapted to the concerns of sustainable development. Under(More)
We define and study a detailed many body model for the muscular contraction taking into account the various myosin heads. The state of the system is defined by the position of the actin and by an internal coordinate of rotation for each myosin head. We write a system of Fokker-Planck equations and calculate the average for the position, the number of(More)
The Carnot efficiency of usual thermal motors compares the work produced by the motor to the heat received from the hot source, neglecting the perturbation of the cold source: thus, even if it may be appropriate for industrial purposes, it is not pertinent in the scope of sustainable development and environment care. In the framework of stochastic dynamics(More)
The destruction of quantum coherence can pump energy into a system. For our examples this is paradoxical because the destroyed correlations are ordinarily considered negligible. Mathematically the explanation is straightforward and physically one can identify the degrees of freedom supplying this energy. Nevertheless, the energy input can be calculated(More)
Efficiency at maximum power is studied for two simple engines (three- and five-state systems). This quantity is found to be sensitive to the variable with respect to which the maximization is implemented. It can be wildly different from the well-known Curzon-Ahlborn bound (one minus the square root of the temperature ratio), or can be even closer than(More)
In this work, we consider the nonequilibrium thermodynamics of a reaction-diffusion system at a given temperature, using the Master equation. The information potential is defined as the logarithm of the stationary state. We compare the approximations, given by the Fokker–Planck equation and the Wentzel-Kramers-Brillouin method directly applied to the Master(More)
Many thermodynamic relations involve inequalities, with equality if a process does not involve dissipation. In this article we provide equalities in which the dissipative contribution is shown to involve the relative entropy (a.k.a. Kullback-Leibler divergence). The processes considered are general time evolutions both in classical and quantum mechanics,(More)
In this article, we define stochastic dynamics for a system coupled to reservoirs. The rules for forward and backward transitions are related by a generalized detailed balance identity involving the system and its reservoirs. We compare the variation of information and of entropy. We define the Carnot dissipation and prove that it can be expressed in terms(More)