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What if you destroy the entanglement by destroying one of the entangled particles? You can't do this by shooting it with a particle accelerator, or else the ent

What if you destroy the entanglement by destroying one of the entangled particles? You can't do this by shooting it with a particle accelerator, or else the entanglement infects whatever you hit it with; but you could use an intense field like sending a photon into a black hole or an atom into a neutron star to be ripped apart. Is there a rule for describing the entanglement of the resulting constituent particles with the pre-existing particle? If it's possible to actually break entanglement(so that measurement of a qubit resets to 50%-50% random), it seems like you could transmit information faster than light by preparing a 100%-0% distribution with quantum gates and destroying the particles. Then the first particle would change the distribution of its measurements. And so you could prepare 1000 qubits and measure them every hour, waiting to observe a change.

lisper 10y ago
> What if you destroy the entanglement That is a very good idea, but doesn't work. The only way to "destroy an entanglement" is to bring the entangled particles back together. http://www.flownet.com/ron/QM.pdf http://www.flownet.com/ron/QM.pdf or the movie version: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc And if you get through those you might enjoy this one too: http://blog.rongarret.info/2014/10/parallel-universes-and-arrow-of-time.html http://blog.rongarret.info/2014/10/parallel-universes-and-ar...
- MichaelBurge 10y ago
  > That doesn't work. The only way to "destroy an entanglement" is to bring the entangled particles back together. Suppose a proton A is entangled with a proton B. If B hits an anti-proton C, it gets converted into pure energy(maybe light and heat?). If it's impossible to destroy entanglement, then the subsystem consisting of the light and heat must be entangled with the original particle. Observations: * The dimension of the vector space has increased, since there may be many constituent photons released. So it may be impossible to assign a specific dimension to any quantum state. * What is the rule for determining the resulting quantum state? Is there a book or article? * If you convert a particle entirely into an electromagnetic wave or gravitational waves, and then reconstruct it, does that preserve entanglement? What is the rule for describing how the dimension of the vector space changes as it undergoes multiple transformations? If entanglement is allowed to propagate to a continuous field, then it seems like you'd have an uncountable infinite dimensional vector space to describe its state.
  - lisper 10y ago
    > the subsystem consisting of the light and heat must be entangled with the original particle Yes. Exactly right. That is how/why decoherence happens. That is the reason the universe appears to be classical, and why the arrow of time seems to move in only one direction. The rest of your questions are essentially asking me to teach you all of QM, and that's obviously not possible in an HN comment. You'll have to take a class or read a book.
AgentME 10y ago
Nothing you do to one of the particles is going to noticeably affect anything about the other particle's measurement by itself. Any link between the particles is only apparent by comparing both the measurements together. Imagine you had a machine print out two envelopes with the same random number inside. You and a friend take these envelopes and each go 1 lightyear in separate directions. When you open your envelope, you will instantly know what number was in your friend's envelope. There's no usable FTL communication here. Burning your envelope won't communicate anything FTL to your friend. This just means that when you meet up again, he'll say he believes that you got a 7, and you'll say that he's wrong because you threw away the entanglement first by burning your envelope without looking at it. There are plenty of interesting quirks about about quantum entanglement that this model doesn't contain, but it should cover the lack of FTL communication potential correctly.

lisper 10y ago

> What if you destroy the entanglement That is a very good idea, but doesn't work. The only way to "destroy an entanglement" is to bring the entangled particles back together. http://www.flownet.com/ron/QM.pdf http://www.flownet.com/ron/QM.pdf or the movie version: https://www.youtube.com/watch?v=dEaecUuEqfc https://www.youtube.com/watch?v=dEaecUuEqfc And if you get through those you might enjoy this one too: http://blog.rongarret.info/2014/10/parallel-universes-and-arrow-of-time.html http://blog.rongarret.info/2014/10/parallel-universes-and-ar...

MichaelBurge 10y ago
> That doesn't work. The only way to "destroy an entanglement" is to bring the entangled particles back together. Suppose a proton A is entangled with a proton B. If B hits an anti-proton C, it gets converted into pure energy(maybe light and heat?). If it's impossible to destroy entanglement, then the subsystem consisting of the light and heat must be entangled with the original particle. Observations: * The dimension of the vector space has increased, since there may be many constituent photons released. So it may be impossible to assign a specific dimension to any quantum state. * What is the rule for determining the resulting quantum state? Is there a book or article? * If you convert a particle entirely into an electromagnetic wave or gravitational waves, and then reconstruct it, does that preserve entanglement? What is the rule for describing how the dimension of the vector space changes as it undergoes multiple transformations? If entanglement is allowed to propagate to a continuous field, then it seems like you'd have an uncountable infinite dimensional vector space to describe its state.
- lisper 10y ago
  > the subsystem consisting of the light and heat must be entangled with the original particle Yes. Exactly right. That is how/why decoherence happens. That is the reason the universe appears to be classical, and why the arrow of time seems to move in only one direction. The rest of your questions are essentially asking me to teach you all of QM, and that's obviously not possible in an HN comment. You'll have to take a class or read a book.

AgentME 10y ago

Nothing you do to one of the particles is going to noticeably affect anything about the other particle's measurement by itself. Any link between the particles is only apparent by comparing both the measurements together. Imagine you had a machine print out two envelopes with the same random number inside. You and a friend take these envelopes and each go 1 lightyear in separate directions. When you open your envelope, you will instantly know what number was in your friend's envelope. There's no usable FTL communication here. Burning your envelope won't communicate anything FTL to your friend. This just means that when you meet up again, he'll say he believes that you got a 7, and you'll say that he's wrong because you threw away the entanglement first by burning your envelope without looking at it. There are plenty of interesting quirks about about quantum entanglement that this model doesn't contain, but it should cover the lack of FTL communication potential correctly.