Large deviations in the alternating mass harmonic chain

We extend the work of Kannan et al. and derive the cumulant generating function for the alternating mass harmonic chain consisting of N particles and driven by heat reservoirs. The main result is a closed expression for the cumulant generating function in the thermodynamic large N limit. This expression is independent of N but depends on whether the chain consists of an even or an odd number of particles, in accordance with the results obtained by Kannan el al. for the heat current. This result is in accordance with the absence of local thermodynamic equilibrium in a linear system.Comment: 19 pages latex, 6 figures, final version, appeared in J. Phys. A: Math. Theor 47, 325003 (2014

Heat fluctuations and fluctuation theorems in the case of multiple reservoirs

We consider heat fluctuations and fluctuation theorems for systems driven by multiple reservoirs. We establish a fundamental symmetry obeyed by the joint probability distribution for the heat transfers and system coordinates. The symmetry leads to a generalisation of the asymptotic fluctuation theorem for large deviations at large times. As a result the presence of multiple reservoirs influence the tails in the heat distribution. The symmetry, moreover, allows for a simple derivation of a recent exact fluctuation theorem valid at all times. Including a time dependent work protocol we also present a derivation of the integral fluctuation theorem.Comment: 27 pages, 1 figure, new extended version, to appear in J. Stat. Mech, (2014

Energetics and efficiency of a molecular motor model

The energetics and efficiency of a linear molecular motor model proposed by Mogilner et al. (Phys. Lett. 237, 297 (1998)) is analyzed from an analytical point of view. The model which is based on protein friction with a track is described by coupled Langevin equations for the motion in combination with coupled master equations for the ATP hydrolysis. Here the energetics and efficiency of the motor is addressed using a many body scheme with focus on the efficiency at maximum power (EMP). It is found that the EMP is reduced from about 10 pct in a heuristic description of the motor to about 1 per mille when incorporating the full motor dynamics, owing to the strong dissipation associated with the motor action.Comment: 23 pages, 6 figures, final version, appeared in J. Stat. Mech. P12001 (2013

Bound particle coupled to two thermostats

We consider a harmonically bound Brownian particle coupled to two distinct heat reservoirs at different temperatures. We show that the presence of a harmonic trap does not change the large deviation function from the case of a free Brownian particle discussed by Derrida and Brunet and Visco. Likewise, the Gallavotti-Cohen fluctuation theorem related to the entropy production at the heat sources remains in force. We support the analytical results with numerical simulations

Localized growth modes, dynamic textures, and upper critical dimension for the Kardar-Parisi-Zhang equation in the weak noise limit

A nonperturbative weak noise scheme is applied to the Kardar-Parisi-Zhang equation for a growing interface in all dimensions. It is shown that the growth morphology can be interpreted in terms of a dynamically evolving texture of localized growth modes with superimposed diffusive modes. Applying Derrick's theorem it is conjectured that the upper critical dimension is four.Comment: 10 pages in revtex and 2 figures in eps, a few typos correcte

Aspects of heat currents in qubit systems

There is a current interest in quantum thermodynamics in the context of open quantum systems. An important issue is the consistency of quantum thermodynamics, in particular the second law of thermodynamics, i.e., the flow of heat from a hot reservoir to a cold reservoir. Recent emphasis has been on composite system. Here we discuss two cases, namely as an example a single qubit and as a simple composite system two coupled qubits driven by two heat reservoirs at different temperatures, respectively. Ignoring coherence effects we present explicit expressions for the heat currents in agreement with the second law of thermodynamics. The analysis is carried out in the Born-Markov approximation.Comment: 18 pages, 2 figures, latex, second version: Stated explicitly that calculation of heat currents ignores coherence effect