The temperature has a certain uncertainty that can’t be reduced, but this allows us to take it into account. One issue, in particular, is the superposition of the energy states. The concept of superposition has been made famous by physicist Erwin Schrödinger. In his thought experiment, a cat is trapped in a box with a vial of poison that can be activated by a quantum process.
Since the scientist doesn’t know what’s happening in there, the cat is both alive and dead – it exists in two states at the same time. For the thermometer, this happens for temperature states. The findings are important for the design of optimal nanoscale thermometers. These might not be useful in everyday life, but they will play a pivotal role in the successful functioning of many upcoming technologies.
“In the quantum case, a quantum thermometer… will be in a superposition of energy states simultaneously,” author Harry Miller, from the University of Exeter, told Live Science. “What we find is that because the thermometer no longer has a well-defined energy and is actually in a combination of different states at once, that this actually contributes to the uncertainty in the temperature that we can measure.”