In this talk, I will present our recent work on investigating quantum advantages in loss sensing with the two-mode squeezed vacuum state. Following an experimental demonstration in PRX 4, 011049, we consider a quantum scheme in which the signal mode is passed through the target and a thermal noise is introduced to the idler mode before they are measured. We consider two detection strategies of practical relevance: coincidence-counting and intensity-difference measurement, which are widely used in quantum sensing and imaging experiments. By computing the signal-to-noise ratio, we verify that quantum advantages persist even under strong thermal background noise compared to the classical scheme which uses a single-mode coherent state that directly suffers from the thermal noise. We then consider a different setup in which the thermal noise is introduced to the signal mode in the quantum schemes. We show that the quantum advantages are significantly reduced in such a setup. Remarkably, however, under an optimum measurement scheme associated with the quantum Fisher information, we show that the two-mode squeezed vacuum state does exhibit a quantum advantage over the entire range of the environmental noise and loss.

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