Quadratic Enhancement in the Reliability of Collective Quantum Engines

We study fluctuations in many-body quantum heat engines operating in the presence of collective system-bath interactions. We show that collective effects in open quantum systems can be harnessed to develop highly consistent many-body quantum engines. We consider quantum Otto engines, modeled by $n$ spins collectively coupled to thermal baths. Our results show that collective effects can significantly reduce the fluctuations in the output work, quantified by high reliability ($r$) and low thermodynamic uncertainty. In contrast to independent engines, we demonstrate a quadratic enhancement of the reliability $r$ for their collective counterparts. We extend our analysis to the case of interacting spin models commonly studied in many-body physics, such as the Lipkin-Meshkov-Glick (LMG) model, thereby broadening the regime of applicability of collective effects in quantum thermal machines significantly. This paves the way forward for realistic collective quantum thermal machines in many body systems.