Nanoscale Heat Engine Beyond the Carnot Limit

TLDR

A quantum Otto cycle with a time‑dependent harmonic oscillator coupled to a squeezed thermal reservoir is considered. The authors propose an experimental scheme using a single trapped ion in a linear Paul trap with special geometry to implement the model. Analytical investigations and Monte Carlo simulations support the feasibility of the proposed trapped‑ion implementation. The efficiency at maximum power rises with squeezing, exceeding the Carnot limit and reaching up to four times higher for realistic trap parameters.

Abstract

We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the efficiency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the efficiency at maximum power of up to a factor of 4 is reached, largely exceeding the Carnot bound.