Experimental realization of a minimal microscopic heat engine

Argun, Aykut; Soni, Jalpa; Dabelow, Lennart; Bò, Stefano; Pesce, Giuseppe; Eichhorn, Ralf; Volpe, Giovanni

doi:10.1103/physreve.96.052106

Cited by 105 publications

(119 citation statements)

References 47 publications

(77 reference statements)

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“…experimental measurements, such as those performed in Ref. [31]. Lastly, we stress that the quantities discussed above may be interpreted physically, as thermodynamic quantities, in particular.…”

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confidence: 86%

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Asymmetry relations and effective temperatures for biased Brownian gyrators

et al. 2018

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We focus on a paradigmatic two-dimensional model of a nanoscale heat engine, -the so-called Brownian gyrator -whose stochastic dynamics is described by a pair of coupled Langevin equations with different temperature noise terms. This model is known to produce a curl-carrying non-equilibrium steady-state with persistent angular rotations. We generalize the original model introducing constant forces doing work on the gyrator, for which we derive exact asymmetry relations, that are reminiscent of the standard fluctuation relations. Unlike the latter, our relations concern instantaneous and not time averaged values of the observables of interest. We investigate the full two-dimensional dynamics as well as the dynamics projected on the x-and y-axes, so that information about the state of the system can be obtained from just a part of its degrees of freedom. Such a state is characterized by effective "temperatures" that can be measured in nanoscale devices, but do not have a thermodynamic nature. Remarkably, the effective temperatures appearing in full dynamics are distinctly different from the ones emerging in its projections, confirming that they are not thermodynamic quantities, although they precisely characterize the state of the system. While in the past statistical physics has been mainly devoted to the microscopic basis of the macroscopic behaviour, present day research is largely addressing "small" or non-thermodynamic systems, which either evolve spontaneously or are subjected to external drivings and constraints. Unlike macroscopic systems, that are by and large described by thermodynamics and linear response theory, these systems are still hard to be framed within a comprehensive theory.In fact, macroscopic observations amount to drastic projections from highly dimensional spaces to spaces of observables that consist of just a few dimensions. This is the reason why thermodynamics is so universal; those projections loose an enormous amount of information about the microscopic dynamics, hence the properties of observables only minimally depend on such microscopic details, provided a few conditions are met. Basically, it suffices that atomic forces are short ranged and repulsive. Then, universality as well as the equivalence of ensembles are established, and the resulting theory of macroscopic objects very generally holds. On the contrary, the behavior of systems made of a non-thermodynamic number of elementary constituents strongly depends on all defining parameters, and a theory as widely applicable as thermodynamics can hardly be envisaged.Nevertheless, one common facet of such systems is that their observables undergo non-negligible fluctuations. Therefore, the seminal paper [1] represents a pioneering attempt towards a unified theory of fluctuating phenomena [2,3]. Its chief result is called Fluctuation Relation (FR), and it constitutes one of the first exact results obtained for systems which are almost arbitrarily far from equilibrium. Close to equilibrium the FR reproduces the Green-Kubo and Onsager re...

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confidence: 86%

“…An experimental realization of gyrators was developed also in Ref. [31], in a framework that can be generalized to include our model settings; that being, constant bias exerted on the gyrator.…”

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confidence: 99%

Asymmetry relations and effective temperatures for biased Brownian gyrators

et al. 2018

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“…Here η i (t) is an independent Gaussian white-noise with η i (t) = 0 and η i (t)η j (t ) = δ ij δ(t − t ). For a particular range of parameters where the matrix A is positive definite, the system reaches a non-equilibrium steady state with the following probability distribution [51] P ss (x) = 1…”

Section: Acknowledgmentsmentioning

confidence: 99%

Inferring Entropy Production from Short Experiments

2020

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We provide a strategy for the exact inference of the average as well as the fluctuations of the entropy production in non-equilibrium systems in the steady state, from the measurements of arbitrary current fluctuations. Our results are built upon the finite-time generalization of the thermodynamic uncertainty relation, and require only very short time series data from experiments. We illustrate our results with exact and numerical solutions for two colloidal heat engines. arXiv:1910.00476v2 [cond-mat.stat-mech]

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“…In the context of Brownian motion, such a ratchet has been modelled, for example, with asymmetric objects moving in separate thermal baths [16][17][18]. Another class of autonomous machines is represented by Brownian gyrators [19][20][21] where a Brownian particle in a parabolic asymmetric potential rotates around potential minimum when connected to two different heat reservoirs. The particle mean rotation velocity in the phase space can be calculated [20], although the problem of how to extract useful work from such a setup has not been addressed.…”

Section: Introductionmentioning

confidence: 99%

A minimal model of an autonomous thermal motor

Fogedby¹,

Imparato²

2017

EPL

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We consider a model of a Brownian motor composed of two coupled overdamped degrees of freedom moving in periodic potentials and driven by two heat reservoirs. This model exhibits a spontaneous breaking of symmetry and gives rise to directed transport in the case of a nonvanishing interparticle interaction strength. For strong coupling between the particles we derive an expression for the propagation velocity valid for arbitrary periodic potentials. In the limit of strong coupling the model is equivalent to the Büttiker-Landauer model [1-3] for a single particle diffusing in an environment with position dependent temperature. By using numerical calculations of the Fokker-Planck equation and simulations of the Langevin equations we study the model for arbitrary coupling, retrieving many features of the strong coupling limit. In particular, directed transport emerges even for symmetric potentials. For distinct heat reservoirs the heat currents are well-defined quantities allowing a study of the motor efficiency. We show that the optimal working regime occurs for moderate coupling. Finally, we introduce a model with discrete phase space which captures the essential features of the continuous model, can be solved in the limit of weak coupling, and exhibits a larger efficiency than the continuous counterpart. IntroductionThere is currently numerous scientific investigations aimed at characterizing the functioning of micro and nano-motors. There has, for example, been a rapid development of various artificial nanomotors with the aim of mimicking the performance of biological machines [4][5][6].From the point of view of man-made engineered micro and nano-motors, ideally one would like to design autonomous machines which are able to cyclically extract energy from the resources available in the environment and convert it to useful work. Similarly to their macroscopic counterparts, such machines must be driven outof-equilibrium by means of one or more thermodynamic forces.In the present paper we focus in particular on a motor driven by temperature gradients. A Brownian motor has long been the paradigmatic model for a microscopic machine, working either in time-dependent or steady state conditions. One well known example is a Brownian particle moving in a periodic and asymmetric potential, a so-called ratchet potential. In such a spatially periodic system, the breaking of the spatial inversion symmetry and of thermal equilibrium, obtained by modulating the force acting on the particle, results in the emergence of directed transport [7][8][9]. Another typical example is represented by a Brownian particle driven by both a periodic temperature variation and an external parameter, periodically changing the system energy [10,11]. This model, which mimics the operation of a heat engine cyclically in contact with different heat reservoirs, has been implemented in a recent experiment [12]. In all these models there is an external agent that changes periodically some parameters, typically a thermodynamic force, according to the moto...

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Experimental realization of a minimal microscopic heat engine

Cited by 105 publications

References 47 publications

Asymmetry relations and effective temperatures for biased Brownian gyrators

Asymmetry relations and effective temperatures for biased Brownian gyrators

Inferring Entropy Production from Short Experiments

A minimal model of an autonomous thermal motor

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