Otto and stirling engines in a system of three entangled qubits in a ring topology

Abstract

This study explores the thermodynamic behavior of a system comprising three spin-1/2 particles, modeled using a Heisenberg XXX-type arrangement in a ring topology. The system’s performance as quantum Stirling, quasistatic Otto, and quantum Otto engines near two Quantum Critical Points (QCPs) is investigated, with an external magnetic field serving as the control parameter. The research focuses on the quantum phase transitions at B = 0 and B = 3J in the antiferromagnetic system, examining their impact on engine efficiency through entanglement and spin correlation analyses. Results indicate that the Stirling engine performs optimally at low temperatures, achieving Carnot efficiency at the lower QCP, while the Otto engines are more efficient at higher temperatures, with the quasistatic engine reaching Carnot’s efficiency at the higher QCP. The study also reveals a deep interrelationship between information theory and thermodynamics, demonstrating that thermodynamic functions in this tripartite system can be expressed through spin correlations. This highlights the intricate link between quantum information and thermodynamic performance, offering insights into the efficiency of quantum thermodynamic cycles near QCPs.