Running summarizing tools on a new article

Abstract: We investigate active Brownian heat engines consisting of a Brownian particle confined in a modulated harmonic potential and immersed in a non-equilibrium bath of variable activity. We show that their average energetics determined by the second moment of the particle position can be mapped onto that of a model with a passive equilibrium bath at a suitably defined time-dependent effective temperature. Formal limitations for the thermodynamic performance, including maximum efficiency, efficiency at maximum power, and maximum efficiency at fixed power ensue. They help to clarify the degree to which such active heat engines can outperform passive-bath designs, which has been a debated issue for recent experimental realizations. And they can guide the design of new micro-machines. To illustrate the general principles, we analyze a specific realization of an active heat engine based on the paradigmatic Active Brownian Particle (ABP) model. Explicit analytical and numerical results are provided and discussed for quasi-static and finite-rate protocols. They reveal some non-intuitive features of the dynamical effective temperature, which complicate the implementation of classical cycles (like Carnot or Stirling) with active baths, illustrate various conceptual and practical limitations of the effective-equilibrium mapping, and clarify the operational relevance of various coarse-grained measures of dissipation.