Out-of-equilibrium quantum thermochemical engine with one-dimensional Bose gas

We theoretically investigate the finite-time performance of a quantum thermochemical engine utilizing a harmonically trapped one-dimensional (1D) Bose gas in the quasicondensate regime as the working fluid. The proposed engine operates in an Otto cycle, where the unitary work strokes are simulated through a quench of the interatomic interactions of the 1D Bose gas. In the work strokes, the working fluid is treated as a closed quantum many-body system that undergoes dynamic evolution, beginning from an initial thermal equilibrium state at a nonzero temperature. On the other hand, during the thermalization strokes, the working fluid is treated as an open many-body quantum system in diffusive contact with a thermal reservoir, allowing particle exchange alongside the transfer of heat. Using a c-field approach, we demonstrate that the engine's operation is enabled by the chemical work done on the working fluid through the flow of particles from the hot reservoir. We examine the finite-time performance of the proposed quantum thermochemical engine in two extreme regimes: (i) the out-of-equilibrium regime (sudden quench), which yields near-maximum power (due to fast driving of the system) while compromising efficiency, and (ii) the quasistatic (near-adiabatic) limit, which approaches maximum efficiency but generates zero power output due to slow driving of the system. Notably, we show that using chemical work allows the engine to achieve efficiencies close to the near-maximum (quasistatic) limit, even in the out-of-equilibrium regime, while maintaining high power output. Thus, in the out-of-equilibrium operational regime, our proposed engine provides a favorable trade-off between efficiency and power output. We also draw connections to previous research, particularly the case of an adiabatic engine cycle operating at zero temperature. We show that this zero-temperature scenario establishes an upper bound on the efficiency and work of our proposed thermochemical engine operating at nonzero temperatures.