When we learn about heat transfer in school, we learn there are three types: conduction, convection, and radiation. But scientists have a fourth type of heat transfer, and it's all thanks to quantum mechanics.
One main principle of quantum mechanics is so-called zero-point energy, or vacuum fluctuations. This means that, even at a temperature of absolute zero, a system will still have some amount of energy. This causes all sorts of bizarre phenomena, like particles randomly popping in and out of existence near a black hole, or, in this case, photons popping in and out of existence between two plates of metal. Known as the Casimir effect, these short-lived, "virtual" photons can transfer energy from one of the metal plates to the other.
The scientists observed the effect in this new experiment by making the metal plates out of a deform-able material that can vibrate like the head of a drum. Each of these drumheads were tethered to blocks at different temperatures. Heat from the blocks caused the atoms in the plates to jiggle faster, making them vibrate. But because the blocks were at different temperatures, the two drumheads vibrated with different amounts of energy. When they were brought close enough together, the scientists saw that the Casimir photons took energy from the hotter drumhead and transported it across the vacuum to the cooler one, until the two were in thermal equilibrium.
Overall, the influence of quantum mechanics on everyday human experiences like temperature is a hot research area, and I personally find it pretty cool!