

Entanglement Makes Quantum Particles Measurably Heavier - jcr
https://medium.com/the-physics-arxiv-blog/entanglement-makes-quantum-particles-measurably-heavier-says-quantum-theorist-6fbd1e1e3eee

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gus_massa
> _Bruschi’s idea is simple in principle. Physicists have long known that a
> single quantum particle can exist in two places at the same time. There is a
> clear quantum correlation called entanglement between these two locations
> that is well-defined mathematically in quantum mechanics._

I don't like this sentence. I've read about entanglement between two
particles. I have Math Ph.D. and a 50% Physics major. Can someone with a 100%
Physic major explain if this is correct? Is this related to quantum gravity?

> _Don’t hold your breath, however. Bruschi has carried out some back-of-
> an—envelope calculations of the size of the effect for a quantum particle
> with the mass of an electron, of the order of 10^-31 kilograms. He says the
> change in this particle’s weight when it is entangled in two locations is
> just one part in 10^[-]37. Inconceivably small._

10^{-37} Kg ~= 56 meV ~=2 mHartrees
[http://www.wolframalpha.com/input/?i=10%5E%28-37%29kg+*+c%5E...](http://www.wolframalpha.com/input/?i=10%5E%28-37%29kg+*+c%5E2+to+hartree)

In quantum mechanics there are a lot of examples with a lot of correlation
(it's similar to like entanglement) and using spectrometry technics I think
that it's possible to measure a few mHartrees.

~~~
ThePhysicist
Yes indeed this sentence seems very wrong to me as well: The author seems to
mistake entanglement for superposition. The former describes a quantum state
that involves TWO quantum systems whose wave functions are "intertwined" such
that you cannot write it as a simple product of the wavefunction of either
system (a so-called "product state"), and which thus produces some seemingly
paradoxical effects (e.g. the famous Einstein-Podolsky-Rosen paradox).
Superposition, on the other hand, means that a SINGLE quantum system can have
a wave function in which the system is in more than one possible state at
once.

Or, in mathematical terms, here's an entangled state

|\psi> = 0.5^(1/2) _(|0 >_|1> \+ |1> _|0 >)

If we would make a measurement of the first quantum state, we would project it
to either the |0> or the |1> state. This would result in the state of the
other system to be projected into either the |1> or the |0> state,
respectively. So there is some strange, "spooky" action between the two
seemingly independent states.

Here is a superposition state for comparison:

|\psi> = 0.5^(1/2)_(|0>+|1>)

Note that it involves only a single quantum system, which has a 50 % amplitude
in either of the states 0 or 1.

Wikipedia has some good definitions of entanglement and superposition:

[https://en.wikipedia.org/wiki/Quantum_entanglement](https://en.wikipedia.org/wiki/Quantum_entanglement)
[https://en.wikipedia.org/wiki/Quantum_superposition](https://en.wikipedia.org/wiki/Quantum_superposition)

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krick
Ugh, I understand that there's limit for how long title could be, but there
really is a difference between "Entanglement Makes Quantum Particles
Measurably Heavier" and "Entanglement Makes Quantum Particles Measurably
Heavier, Says Quantum Theorist". When I saw the title my eyes got wider and I
was wondering why it's even on medium, but then I followed the link and saw
magic dust fading out. Turns out, nothing really happened. Not yet, anyway.

~~~
cLeEOGPw
I was reading and looking for where the experiments prove the claim in the
title, but there is none. Just a theory so far.

