[__Joker]

High school educated talking here.

Does Quantum Entanglement have any promise for instantaneous communication (theoretically) ?

[karmakurtisaani]

Nope, you can't pass information through entangled particles. All you know when you measure you particle is that the other one will turn out the same (or is likely to, I forgot the exact details). This does not lend itself to any communication protocol.

[explaininjs]

Nope, entangled pairs are basically the following in JS:

    class RawQuantum { 
      value = () => this._hidden ??= Math.random() 
    }

    class EntangledQuantum extends RawQuantum {
      valueA = () => this.value()
      valueB = () => 1 - this.value()
    }

    const {valueA, valueB} = new EntangledQuantum()

You can give valueA to one procedure and valueB to another and know that whenever the _hidden field is observed, the two will have complementary views of the data. But this doesn't give the two procedures any way to communicate, and there's no measurable difference between resolving the _hidden filed now or later.

[moefh]

That only works if you replace "basically" with "not really". With this code you can't violate Bell's inequalities[1], which is a really important feature of Quantum Mechanics.

[1] https://en.wikipedia.org/wiki/Bell%27s_theorem

[OkayPhysicist]

To elaborate somewhat on the basically, the key difference between this example (and the more common "put a left shoe in one shoebox, a right shoe in another, shuffle, and send each to different people" example) and actual quantum entanglement involves being able to choose from a multi-axis spectrum of different measurements, and the resulting level of correlation precluding the possibility of there being a local hidden variable (the leftness or rightness of the shoe in the box before opening).

[chrismarlow9]

https://news.fnal.gov/2020/12/fermilab-and-partners-achieve-....

[OkayPhysicist]

That's about transmitting qubit-encoded information. It has absolutely nothing, at all, to do with FTL communication. It's a somewhat more elegant solution than USPS for solving the problem of "I have a qubit here, I want to move it over there".

[wiml]

It probably doesn't, but if it does, it could be used to send messages back in time. Relativity doesn't care how something goes FTL, it's just really clear there's no room for "FTL but not time travel" unless you introduce some odd and unphysical-seeming extra restrictions on the universe.