ΔTnoise in mesoscopic hybrid junctions: influence of barrier strength and thermal bias

Quantum noise is a fundamental probe of quantum transport phenomena, offering insights into current correlations and wave-particle duality. A particularly intriguing form of such noise,ΔTnoise, emerges under a finite temperature difference in the absence of charge current at zero voltage bias. In this work, we investigateΔTnoise in mesoscopic hybrid junctions incorporating insulating barriers, where the average charge current remains zero at zero bias. Using quantum shot noise measurements, we demonstrate thatΔTnoise in metal-insulator-superconductor junctions is approximately 16 times greater than in metal-insulator-metal counterparts. Our analysis further reveals thatΔTnoise exhibits a non-monotonic dependence on barrier strength-rising to a peak before declining-while increasing monotonically with the applied temperature bias. These findings underscore the rich interplay between thermal gradients and barrier properties in determining quantum noise characteristics in hybrid mesoscopic systems.