How hot is Schrodinger’s coffee?
August 14, 2018, University of Exeter
A new uncertainty relation, linking the precision with which temperature can be measured and quantum mechanics, has been discovered at the University of Exeter.
If you measure the temperature of your coffee with a standard over-the counter thermometer you may find 90°C give or take 0.5°C. The temperature uncertainty in your reading arises because the mercury level in the thermometer fluctuates a little bit, due to microscopic collisions of the mercury atoms.
Things become more interesting when trying to measure the temperature of small objects, such as nanometer devices or single cells. To obtain precise measurements one needs to use tiny nanoscale thermometers made up of just a few atoms.
The team at Exeter has developed a new theoretical framework that allows the characterisation of small-scale thermometers and establishes their ultimate achievable accuracy. It turns out that under certain circumstances the uncertainty in temperature readings are prone to additional fluctuations, which arise because of quantum effects.
Specifically, tiny thermometers can be in a superposition between different temperatures, e.g. 90.5°C and 89.5°C, just like Schrödinger’s cat can be in a superposition between being dead and alive.
So I guess “Size Matters” ;-)