Quantum Computing

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Quantum entanglement could connect drones for disaster relief, bypassing traditional networks (phys.org)

submitted 2 weeks ago by cm0002@no.lastname.nz to c/qubits@mander.xyz

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Any time you use a device to communicate information—an email, a text message, any data transfer—the information in that transmission crosses the open internet, where it could be intercepted. Such communications are also reliant on internet connectivity, often including wireless signal on either or both ends of a transmission.

But what if two—or 10, or 100, or 1,000—entities could be connected in such a way that they could communicate information without any of those security or connectivity concerns?

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[–] bunchberry@lemmy.world 2 points 2 weeks ago* (last edited 2 weeks ago)

Yes, but there isn't a consensus that the "quantum state" is actually a physical thing. It is not observable in a single experiment but only over an ensemble of experiments where you vary the measuring apparatus's settings over the ensemble. An ensemble is just a fancy way in physics of saying an idealized situation where the same experiment is conducted an infinite number of times such that it approaches the idealized statistical distribution of the results.

The quantum state contains more information than the classical state, but if the quantum state is only observable over an ensemble of systems, then this shouldn't be surprising because an ensemble by its very nature is more complicated. An infinite number of experiments conducted where each contain different initial conditions obviously will contain more information than a single experiment will.

There is thus a lot of debate in the literature over whether or not the quantum state is (1) a physical thing (called psi-ontic), (2) a statistical thing (called psi-epistemic), or (3) partially statistical and partially physical. There is a popsci misconception that the Copenhagen interpretation says that the quantum state is like a physical wave that spreads out until you look at it then undergoes a "collapse" into a single particle, but if you actually read the writings of people like Bohr and Heisenberg, they insisted on treating it as epistemic and not physical, and they never even talked about "collapse" at all because they did not assert particles spread out as quantum waves in the first place to need to "collapse" back into a particle.

Of course, you can believe the quantum state is physical. That is a valid point of view. Psi-ontic interpretations are very common. But I just want to point out that there is a bit more nuance in the literature and not a consensus on it and so not every physicist would readily agree that something is actually being instantaneously teleported in quantum teleportation, although some others would agree to that statement.