# Squeezed thermal reservoirs as a resource for a nano-mechanical engine beyond the Carnot limit

## TL;DR

This paper demonstrates that nano-mechanical engines coupled to squeezed thermal reservoirs can surpass the traditional Carnot efficiency limit, revealing new possibilities in non-equilibrium thermodynamics at small scales.

## Contribution

It provides the first experimental evidence that squeezed thermal reservoirs enable heat engines to operate beyond the Carnot limit, introducing a novel approach to nano-engine design.

## Key findings

- Efficiency exceeds Carnot limit with squeezed reservoirs
- Single squeezed reservoir can power a cyclic engine
- New regime of non-equilibrium thermodynamics at nanoscale

## Abstract

The efficient conversion of thermal energy to mechanical work by a heat engine is an ongoing technological challenge. Since the pioneering work of Carnot, it is known that the efficiency of heat engines is bounded by a fundamental upper limit, the Carnot limit. Theoretical studies suggest that heat engines may be operated beyond the Carnot limit by exploiting stationary, non-equilibrium reservoirs that are characterized by a temperature as well as further parameters. In a proof-of-principle experiment, we demonstrate that the efficiency of a nano-beam heat engine coupled to squeezed thermal noise is not bounded by the standard Carnot limit. Remarkably, we also show that it is possible to design a cyclic process that allows for extraction of mechanical work from a single squeezed thermal reservoir. Our results demonstrate a qualitatively new regime of non-equilibrium thermodynamics at small scales and provide a new perspective on the design of efficient, highly miniaturized engines.