Entanglement decoherence vs waveform collapse

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I'm sure this has been asked multiple times, but I couldn't easily find a answer.

So in the double slit experiment, with steady source of emission through two slits, we see an interference pattern on the other side that suggests the emission is wave like as it passes the slits.  The emission appears to acknowledge and pass through BOTH slits, while its waveform remains uncollapsed.

What happens if the two slits are entangled such that when one slit is open the other is instantaneously closed, for each emission.   Would the entanglement of the slits cause the waveform of the emission to collapse, or would the waveform cause the slits to decohere?  How would a partial decoherence of the slits affect the probability distribution of where the particle might end up being detected?

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You cannot entangle two classical (macroscopic) objects. But there is no limit to how much entanglement you can get as long as you keep it microscopic and coherent --very delicate interactions. You can entangle a photon to another photon, to another photon, and so on.

People have done that with silicon atoms, and they call it "Schrödinger cats."

On 9/19/2022 at 1:36 PM, joigus said:

The so-called Schrödinger-cat experiments refer to producing quantum superpositions of mesoscopic systems (size bigger than a single elementary particle, but still not daily-life size). The results were published in 2018, it was made with microbeams of silicon 10 micrometers long and 1x0.25 micrometers across, keeping quantum coherence all along. This is the experiment:

That's not the relevant situation with two holes drilled on a plank.

You could correlate each hole with a spin-flip device that's behind at least one of them: If the particle were to go through that hole, the spin would flip. The interference pattern would be broken.

Of course, at the end, you would have to have something amplify the signal. If you don't amplify the signal at any point (making millions and millions of atomic interactions get involved in the process), the interference pattern would still be there.

That's my understanding. I haven't conducted the experiment at home.

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OK yes, the slits themselves do not have to be entangled.   I guess you cant actually entangle a hole.  But perhaps you can have two microscopic holes that are blocked by an entangled pair of particles.  For the sake of clarity, lets just call it an entangled slit.

But this raises another question.  What happens if the two slits are not exactly perpendicular to the wave?  So when the wave reaches one slit first, it would instantaneously close the other before the wave reaches the second slit, thus showing no interference on the detector, as the 2nd slot is closed by the time the wave arrives.

Is this a matter of precision?  Could we position the two slits accurately enough to ensure the wave passes both slits simultaneously?   So accurate as to match the instantaneous decoherence of the entangled slots?   Lets say the wave managed to reach both slits instantaneously.  Would the wave managed to pass through both slits before either of the closed and we see interference, or will the slits close before the wave gets through and we see no interference.

Does the wave function of a quantum system preserve quantum entanglement in another system it encounters.

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