2021/08/24 by Ivan Henao, Henao, Ivan, Karen V. Hovhannisyan +3
Engineering · Physics and Astronomy · #Advanced Thermodynamic Systems and Engines #Calibration and Measurement Techniques #FOS: Physical sciences #Quantum Physics (quant-ph) #Superconducting and THz Device Technology
paper · pdf · doi:10.48550/arxiv.2108.10469
openalex publication_date 2021/08/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Thermal equilibrium states are exponentially hard to distinguish at very low temperatures, making equilibrium quantum thermometry in this regime a formidable task. We present a thermometric scheme that circumvents this limitation, by using a two-level probe that does not thermalize with the sample whose temperature is measured. This is made possible thanks to a suitable interaction that couples the probe to the sample and to an auxiliary thermal bath known to be at a higher temperature. Provided a reasonable upper bound on the temperature of the sample, the resulting 'thermometric machine' drives the probe towards a steady state whose signal-to-noise ratio can achieve values as high as O(1/T). We also characterize the transient state of the probe and numerically illustrate an extreme reduction in the number of measurements to attain a given precision, as compared to optimal measurements on a thermalized probe.