Abstract. We propose employing a quantum heat engine as a sensitive probe for
thermal baths. In particular, we study a single-atom Otto engine operating in an open
thermodynamic cycle. Owing to its cyclic nature, the engine is capable of translating
small temperature differences between two baths into a macroscopic oscillation in a
flywheel. We present analytical and numerical modeling of the quantum dynamics of
the engine and estimate it to be capable of detecting temperature differences as small
as 2 K. This sensitivity can be further improved by utilizing quantum resources such
as squeezing of the ion motion. The proposed scheme does not require quantum state
initialization and is able to detect small temperature differences in a wide range of
base temperatures.