A finite-time quantum Otto engine cycle with tunnel-coupled one-dimensional Bose gases
Dr. Vijit Vinod Nautiyal,
School of Mathematics and Physics, University of Queensland, Australia
IAP Physics Seminar Series will occur on Tuesday 2nd April 24, at 12:30 AM at the UM6P campus (Ryad 8, 1st floor).
Abstract:
Quantum heat engines (QHEs) have been studied extensively in recent years due to two main reasons. Firstly, they provide a well-developed theoretical framework to study the fundamental theories of thermodynamics in the quantum regime. Secondly, they have the potential to leverage truly quantum features, allowing for the development of quantum thermal machines that surpass the performance of their classical counterparts. QHEs with a many-body working fluid allow us to explore ways in which we can exploit many-body effects such as quantum entanglement and quantum correlations to gain the quantum advantage. One-dimensional (1D) Bose gases are regularly realised in experiments with a high degree of control over their internal properties. This makes them an ideal platform to study many-body QHEs.
In this work, we propose a many-body QHE driven by atomic interactions in a weakly interacting 1D Bose gas or a quasicondensate. We use the classical field method to numerically simulate the entire finite-time quantum Otto cycle in an experimentally realisable scenario. In the interaction-induced work strokes of the Otto cycle, the working fluid is treated as an isolated quantum many-body system, undergoing dynamical evolution starting from a thermal state. Whereas in the thermalisation strokes, the working medium is treated like an open quantum system that is in thermal and diffusive contact with a reservoir. To simulate the thermalisation strokes with a finite-size reservoir, we use the tunnel-coupled model of two quasicondensates with an initial temperature and chemical potential imbalance. The finite-time simulation of the complete engine cycle allows us to evaluate the practicality of such engines by calculating the trade-off between efficiency and power output. We demonstrate that for a harmonically trapped Bose gas, engine operation is facilitated by additional chemical work on the working fluid, achieved through particle inflow from the hot reservoir. Thus, the engine effectively functions as a chemical Otto engine. Moreover, in the sudden quench regime (when work strokes are completed in a very short time), the engine operates with maximum power output, while maintaining near-maximum efficiency. Thus, the proposed engine cycle provides a favourable trade-off between the power output and efficiency.
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