In classical mechanics heat and energy are removed from a system either by conduction, convection or radiation. This is because when the system is big enough and there are many particles the models are relatively easy because the actions of any one particle can be ignored. A standard example would be an electron in a wire with a current flowing through it. Although the current can be seen as going from point A to point B each electron is actually moving in a much more erratic way. Scattered by the metal lattice the electrons move randomly with only a trend of travelling towards the positive terminal. This is why drift velocity is surprisingly low for an electron in most wires.
In quantum systems heat becomes even more important. The idea of information and how it can not be destroyed along with various scatterings and thermal breakdowns means that knowing exactly where energy is being dissipated becomes very important. Nanoscale thermometry is the study of this specific section of condensed matter physics. Unfortunately it has remained almost entirely theoretical as the ability to measure temperature on these scales has been extremely limited. Recently however there has been a new thermal probe developed, consisting of a device less than 50 nanometers wide at the end of a sharp pipette. It is, in essence, a quantum thermometer. It can operate all the way down to 4 Kelvin and can record even single electrons gaining or losing energy. This non contact method is many times better than previously designed devices and will no doubt be useful in the future analysis of quantum matter.