New Quantum Principle Suggesting Objects Can be Two Temperatures Simultaneously Rivals 'Schrodinger's Cat'

Tuesday, 18 September 2018 - 11:47AM
Physics
Tuesday, 18 September 2018 - 11:47AM
New Quantum Principle Suggesting Objects Can be Two Temperatures Simultaneously Rivals 'Schrodinger's Cat'
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Image Credit: Pixabay
If Breaking Bad did anything for science literacy, it was introducing the name 'Heisenberg' into pop culture. For those of you who aren't familiar, Werner Heisenberg was the famous German physicist who discovered the eponymous Heisenberg uncertainty principle, which Alok Jha of The Guardian sums up accordingly:

Opening quote
The uncertainty principle says that we cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other.
Closing quote


This wasn't one scientist's attempt at explaining away why his data doesn't fit together—according to Heisenberg, uncertainty is a fundamental property of quantum-level physics. The same applies to energy and temperature: the more you know about a particle's temperature, the less you can know about its energy state, and vice versa. Heisenberg and fellow physicist Niels Bohr claimed that the best way to figure out a particle's temperature would be to stick it into a container or "reservoir" with a uniform temperature, like a powerful refrigerator, then wait until the particle's temperature matched its surroundings, a concept called "thermal equilibrium."

Here's the problem, though: thermal equilibrium is created by the particle and its surroundings exchanging tiny amounts of energy, which happens constantly. The more energy in a particle, the higher its temperature, and vice versa, but that number is changing all the time, preventing you from getting an accurate reading without knowing the exact energy of the particle. But, as you may have guessed, figuring out the precise energy level of a particle involves keeping it from exchanging energy with anything around it...which would preclude the use of a refrigerator.

Now, researchers from the University of Exeter have come up with a device that perfectly expresses this conundrum: a quantum thermometer. According to Harry Miller, one of the physicists involved in the new study: "In the quantum case, a quantum thermometer...will be in a superposition of energy states simultaneously. 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."

To clarify, superposition is what happens when an in object is in two different states at once—the same concept at the heart of Schrodinger's infamous cat thought experiment. So, what does this quantum thermometer idea mean for science? Well, it might actually make things clearer for anyone measuring particles, according to Miller: "Our result is going to tell them exactly how to accurately design their probes and tell them how to account for the additional quantum uncertainty that you get."

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