title: Thermodynamic bounds on efficiency for systems with broken time-reversal symmetry.
abstract: We show that for systems with broken time-reversal symmetry the maximum efficiency and the efficiency at maximum power are both determined by two parameters: a "figure of merit" and an asymmetry parameter. In contrast to the time-symmetric case, the figure of merit is bounded from above; nevertheless the Carnot efficiency can be reached at lower and lower values of the figure of merit and far from the so-called strong coupling condition as the asymmetry parameter increases. Moreover, the Curzon-Ahlborn limit for efficiency at maximum power can be overcome within linear response. Finally, always within linear response, it is allowed to have Carnot efficiency and nonzero power simultaneously .
authors.affiliation: CNISM, CNR-INFM & Center for Nonlinear and Complex Systems, Università degli Studi dell'Insubria, Como, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Benenti
authors.forename: Keiji
authors.initials: K
authors.lastname: Saito
authors.forename: Giulio
authors.initials: G
authors.lastname: Casati