Oh My! Nano Thermometers Are Not Determinant


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” ;-)

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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4 Responses to Oh My! Nano Thermometers Are Not Determinant

  1. D. J. Hawkins says:

    It’s not surprising. In fluid dynamics, very small particles are subject to Brownian motion due to quantum fluctuations in the local fluid space. So even though the bulk speed of the fluid is 5 ft/sec, you may observe very tiny fluctuations where particles are moving at 1 or 20 ft/sec (relative -4 and +15, respectively), albeit over very small distances.

  2. jim2 says:

    All this jumping about isn’t a problem if you just average the readings …

  3. andysaurus says:

    All this jumping about isn’t a problem if you just average the readings …

    Which you do before transferring to your jumping jack flash card.

    [Sorry, just been watching the divine Ms. Franklin singing this song].

  4. Simon Derricutt says:

    When we get down to those dimensions and timescales, there’s no meaning to the number “temperature” anyway, since temperature is the average of the kinetic energies of the particles and really defines the probability of a particle having a particular range of energy when you measure it.

    As such, this may mean that people are moving towards seeing the limitations of temperature measurements, but it also seems they’re trying to make it more complex than it actually is. By its nature, you need a large number of particle collisions to be able to define the temperature, and when you only have a small number of collisions then it’s really not definable.

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