Relativistic quantum Otto engine driven by the circular Unruh effect

Abstract: In this work, we present a new framework for a relativistic quantum analouge of the classical Otto engine. Considering a single qubit as the working substance, we analyse its interaction with a massless quantum scalar field while undergoing two half-circular rotations at ultra-relativistic velocities. The quantum vacuum serves as a thermal bath through the Unruh effect induced due to the acceleration from the circular motions. We observe that the response function of the qubit gets significantly modified by the presence of the qubit's trajectory. Analysing the transition probability behaviour, we find that in the high-acceleration regime, it asymptotically approaches a constant value, determined solely by the properties of the correlation function. Furthermore, our results emphasize the crucial role of the circular trajectory in determining the engine's work output. In particular, the extracted work increases with detector acceleration and approaches an asymptotic limit in the high-acceleration regime. Notably, the efficiency of this model remains unaffected by the circular motion and is consistent with previously studied models.