Entanglement of quantum clocks through gravity

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Entanglement of quantum clocks through gravity

Postby hyksos on March 13th, 2017, 4:56 am 

The idealized picture of space and time in general relativity assigns an ideal clock to each point in space, which tick evenly without being influenced by the nearby clocks. However, when quantum mechanical and gravitational effects are taken into account, this picture is no longer tenable, as the clocks mutually disturb each other and hands of the clocks become "fuzzy."

https://phys.org/news/2017-03-blurred-quantum-world.html
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Re: Entanglement of quantum clocks through gravity

Postby hyksos on March 13th, 2017, 4:58 am 

The clock at the frontal plane of the picture has a relatively high accuracy, depicted by its sharply defined hands. The uncertainty of time reading for this clock is inversely proportional to the energy gap ΔE of the internal degree of freedom that constitutes the clock (Clock Model). By the mass–energy equivalence, the energy of the clock will produce gravitational time dilation effects on nearby clocks. Because the energy is not well defined but has an uncertainty ΔE, nearby clocks will have an uncertainty in their time dilation with respect to the main clock, as depicted by the “fuzzy” hands in a superposition. There exists, therefore, a limitation to the possibility of defining time accurately at nearby points, given by the joint effects of quantum mechanics (superposition principle) and general relativity (gravitational time dilation). This effect is fundamental and independent of the energy gap ΔE of the clock, as stated in Eq. 3.
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http://www.pnas.org/content/early/2017/03/06/1616427114.full
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Re: Entanglement of quantum clocks through gravity

Postby Braininvat on March 13th, 2017, 11:46 am 

Interesting but a little confusing to me. I can see how the gravitational effect would ever so slightly affect, GR-wise, a nearby clock, but if, say, 2 clocks have the same energy (each clock's Hamiltonian, if we consider each clock a "system?") then wouldn't their mutual slowing effects be even, so they would keep the same exact (slightly slower than a single clock in a void) time? I don't see how any quantum superposition effect would be significant here, with macro-scale clock objects. Now, if the clock were some tiny thing, like a Bose-Einstein condensate with some kind of uniform periodicity in its behavior, then maybe that QM thing would become significant?
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