• M. Polettini and M. Esposito, A marginal observer’s effective thermodynamics, arXiv:1703.05715
paper description]

• M. Polettini and M. Esposito, Carnot efficiency at divergent power output,
Eur Phys. Lett. 118, 40003 (2017) , arXiv:1703.05715
[paper description] 

• MP, A. Lazarescu, and M. Esposito, Tightening the uncertainty principle for stochastic currents, Phys. Rev. E 94, 052104 (2016), arXiv:1605.09692
[paper description]

• B. Altaner, MP, and M. Esposito, Fluctuation-Dissipation Relations Far from Equilibrium, Phys. Rev. Lett. 117, 180601 (2016), arXiv:1604.08832
[paper description]

• MP, G. Bulnes Cuetara and M. Esposito, Conservation laws and symmetries in stochastic thermodynamics, Phys. Rev. E 94, 052117 (2016), arXiv:1602.06555
[paper description]

• MP, A. Wachtel and M. Esposito, Dissipation in noisy chemical networks: The role of deficiency, J. Chem. Phys. 143, 184103 (2015), arXiv:1507.00058

• MP, BEST statistics of Markovian fluxes: a tale of Eulerian tours and Fermionic ghosts, J. Phys. A: Math. Theor. 48, 365005 (2015), arXiv:1503.03045
[paper description]

• MP, G. Verley and M. Esposito, Efficiency Statistics at All Times: Carnot Limit at Finite Power, Phys. Rev. Lett. 114, 050601 (2015), arXiv:1409.4716
[paper description]

• MP, Cycle/cocycle oblique projections on oriented graphs, Lett. Math. Phys. 105 , 89-107 (2015), arXiv:1405.0899
[paper description]

• MP and M. Esposito, Transient fluctuation theorem for the currents and initial equilibrium ensembles, J. Stat. Mech. P10033 (2014), arXiv:1408.5941

• MP, Fisher information of Markovian decay modes – Nonequilibrium equivalence principle, dynamical phase transitions and coarse graining, Eur. Phys. J. B 87 (9) , 215 (2014), arXiv:1409.4193

• MP and M. Esposito, Irreversible thermodynamics of open chemical networks I:
Emergent cycles and broken conservation laws
, J. Chem. Phys. 141, 024117 (2014), arXiv:1404.1181

• MP and M. Esposito, Nonconvexity of the relative entropy for Markov dynamics: A Fisher information approach, Phys. Rev. E. 88, 012112 (2013), arXiv:1304.6262

• MP, Fact-checking Ziegler’s maximum entropy production principle beyond the linear regime and towards steady states, Entropy 15, 2570-2584 (2013) [pdf], arXiv:1307.2052

• MP, Generally covariant state-dependent diffusion, J. Stat. Mech. P07005 (2013), arXiv:1206.2798

• MP, Diffusion in nonuniform temperature and its geometric analog, Phys. Rev. E 87, 032126 (2013), arXiv:1211.6580
[paper description]

• MP, Nonequilibrium thermodynamics as a gauge theory, Eur. Phys. Lett. 97, 30003 (2012), arXiv:1110.0608
[paper description]

• MP, Macroscopic constraints for the minimum entropy production principle, Phys. Rev. E 84, 051117 (2011), arXiv:1105.4131

Conference proceedings, Ph.D. thesis, etc.

• MP, System/environment duality of nonequilibrium network observables,
Mathematical Technology of Networks Springer Proceedings in Mathematics & Statistics Volume 128, ed. Delio Mugnolo (Springer, 2015), pp 191-205, arXiv:1106.1280
[paper description]

• MP, Of dice and men. Subjective priors, gauge invariance, and nonequilibrium thermodynamics,
@ JETC2013, Brescia, Italy, July 1-5, 2013. [pdf]

• MP, Geometric and Combiatorial Structures in Nonequilibrium Statistical Mechanics,
Ph. D. thesis, Supervisor: Prof. Armando Bazzani (2012) [pdf]

Other publications

• MP, Unspeakability of love,
Contribution to the interdisciplinary seminar “Being Singular Plural”, Guimaraes, December 2012 [pdf]

• MP, Paul Wilmott e l’abuso della matematica in finanza,
Il Sole 24 Ore, September 02, 2012 (in italian, newspaper title not mine) [pdf]

• MP, Paul Wilmott: lo ‘special QUANT’ e la crisi scientifica della finanza,
Il Corsaro, alternative news site (in italian) [pdf]

Carnot efficiency at divergent power output

New paper out on the arXiv:

MP and M. Esposito, Carnot efficiency at divergent power output,

It’s a very short and straightforward communication on a simple fact that nevertheless might have important consequences, and which was also noticed (one day in advance) in this preprint:

J. S. Lee and H. Park, Carnot efficiency is attainable in an irreversible process, arXiv:1611.07665

Engineering machines that have higher efficiency is a crucial technological problem. It is usually believed that optimal “Carnot” efficiency can only be realized via quasistatic processes that deliver zero power; this fact has been corroborated by several results, including a very recent inequality between power and efficiency by Shiraishi et al. [Phys. Rev. Lett. 117, 190601 (2016)]. However, this conclusion overlooks the important possibility that efficiency can be optimized in a dual scenario, that of divergent power. Starting from an observation that we briefly made in [Phys. Rev. Lett. 114, 050601 (2015)], where in an “extended linear regime” scenario we showed that there exists a limit where Carnot efficiency at divergent power output is possible, in this paper we go beyond the linear regime assumption, showing that, within the formalism of Stochastic Thermodynamics, Carnot efficiency can be achieved in the limit of a divergent power output in arbitrary stationary processes that have two coupled cycles.

Efficiency Statistics at All Times: Carnot Limit at Finite Power

M. Polettini, G. Verley and M. Esposito,
Efficiency Statistics at All Times: Carnot Limit at Finite Power,
Phys. Rev. Lett. 114, 050601 (2015), arXiv:1409.4716

Enhancing the efficiency of energy conversion is the ultimate mission of thermodynamics. According to the paradigms of the phenomenological theory, it has long been believed that high efficiency can only be reached in processes that are infinitely slow and therefore useless for all practical purposes. However, there is no fundamental reason for this, and today we can investigate this question with the tools of a modern and powerful theory called Stochastic Thermodynamics. Stochastic Thermodynamics is capable of treating small systems that fluctuate; while fluctuations usually worsen the accuracy of processes, there exist critical conditions (e.g. near phase transitions) whereby small fluctuations are greatly enhanced, so to become structural properties. Following the proposal of Verley et al. [Verley 2014] to investigate efficiency in a probabilistic way, in this paper we investigate an analytically treatable model, that might be considered as the second-order approximation of any more complex model, where the thermodynamic currents are Gaussian and the efficiency statistics can be calculated exactly. The theory gives remarkable results, in particular there exists a nonvanishing probability that the system operates in reverse mode, i.e. that the power source is actually fed by the device it is supposed to power. This results in a bimodal probability distribution, a prediction of the theory that has already found partial experimental confirmation in an experiment on a small-scale Carnot engine [Martinez 2016]. Furthermore, at critical conditions our analysis shows that the Carnot efficiency can be maintained for long times at finite power output; hence we produced the first theoretical analysis of a system that has high efficiency but that needs not be infinitely slow. This observation has found further substantiation in a recent work relating critical scaling and efficiency enhancement [Campisi 2015]. Finally, other properties of the probability distribution of the efficiency can be shown to be universal, such as its power-law tails which imply that there is no average efficiency but only more probable efficiency. This explains the effect of the divergent average efficiency observed by certain authors in numerical simulations.

[Verley 2014] Verley, G., et al. “The unlikely Carnot efficiency. Nature communications, 5 (2014).

[Martinez 2016] Martínez, I. A., et al. “Brownian carnot engine.” Nature Physics 12.1 (2016): 67-70.

[Campisi 2015] Campisi, M. and Fazio, R. “Universality and scaling of optimal heat engines”, arXiv:1510.06183.