If the temperature difference between two things gets big enough, heat actually just stops flowing entirely.
April 2, 2026
Original Paper
Negative Differential Heat Conductivity in a Harmonic Chain Coupled to a Particle Reservoir
arXiv · 2604.00777
The Takeaway
We usually expect heat to flow faster when the temperature difference is higher, similar to how water flows faster down a steeper hill. In this specific quantum setup, extreme heat causes the system to decouple from its environment, effectively turning a heat source into an insulator.
From the abstract
When coupling thermal baths at different temperatures, negative differential thermal conductivity is typically attributed to nonlinear interactions in the connecting medium. In this work, we demonstrate that such an effect can arise purely from the nature of the thermal baths and their coupling with the medium. Specifically, we construct a bath composed of overdamped thermal particles, which is coupled to one end of a harmonic chain, while the other end is connected to a standard Langevin heat b