Fig. 7
From: Quantum engine efficiency bound beyond the second law of thermodynamics
Squeezing and unsqueezing of a cavity mode. a The interaction of a cavity mode with a squeezed thermal bath (stroke 2 in Fig. 5) may be realised in a micromaser setup where a beam of entangled atom pairs passes through the cavity36. b The unsqueezing operation in stroke 3 of Fig. 5 may be implemented by a suitable modulation of the cavity frequency68,69,70
