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Quantum Interference Between Light Sources Separated by 150M Kilometers
- dboreham 7y agoA bug in the simulator?
- Zenst 7y agoThis wasn't a simulation, unless your going down the universe is a simulation avenue and this is a bug in the matrix route.
- isostatic 7y agoOk, does anyone have a simple guide to what it means?
- eloff 7y agoYeah, I'm really waiting for some of the physics experts on HN to give their take on this. I have a limited understanding of the basic idea behind entanglement, but I can't extend it to this case. I gather this experiment somehow entangles photons from the sun with photons produced by the experimenters, but they're already here when that happens right? So how does the distance come into play. I think I'm probably looking at it too "classically".
- nicholsonpk 7y agoThe diagrams helped clear it up for me (I think.) Yes, they are entangling them on Earth and this seems to be testing the idea that an atom created here is the same/similar enough to one from the sun for this to take place. "Figure 4: Entanglement fidelity measurement of the entangled photon pairs with no common history." It's something I would have assumed as a novice but it's interesting that they thought to test it. If you couldn't entangle them, what would that mean? It looks like the keyword in the title was light "sources" that are 150 Million Kilometers apart. I didn't catch that at first.
- abdullahkhalids 7y ago> created here is the same/similar enough to one from the sun for this to take place Exactly. They are testing if photons on Earth are the same as those produced in the Sun - a very simple test of the translation invariance of the laws of quantum physics. > If you couldn't entangle them, what would that mean? If such experiments failed despite repeated efforts, then maybe the laws of quantum physics are not invariant under translation as far as 150M kilometers. Note that we communicate with Voyager crafts for instance using classical EM waves, so presumably the laws of classical EM work the same as far as the edge of the solar system.
- wwarner 7y agoI'm not an expert, but I thought the paper was more novel than that, in that it challenges my picture of entanglement. The paper demontrates entangled behavior with photons with no common history. They are "identical" in their conserved properties, rather than "entangled" which to me implies that their conserved properties sum to the values that existed before the event that produced the entangled pair. To me, the surprise is that identical pairs always take the same path.
- abdullahkhalids 7y agoThis might challenge your picture of entanglement, but definitely not that of a physicist. Otherwise, I can't make head or tail of your statements.
- wwarner 7y agoI'll try to restate. I was under the impression that entanglement implied what the paper calls "common history", such as when an excited calcium atom decays to its ground state and produces two entangled photons. I also understood entanglement to be particles with some opposite properties, so that the sum of say the angular momentum of the system before and after the decay remains constant. So it was news to me that (a) photons without a common history, and (b) photons indistinguishable in all degrees of freedom could be entangled.
- bmcooley 7y agoI have a limited understanding, but I think this is just further reproduction of the same science. I believe there's some controversy over non-locality in that entanglement and spooky action at a distance is still a result of hidden local variables. By increasing the distance between the sources of the photons, you would give more evidence to nonlocality. Please correct me if this is offbase.
- longtom 7y agoNon-locality means that the way the probability of presence (wave function) of a photon is determined is by trying out all possible paths through the entire universe at once rather than only in regions nearby the photons?
- Misdicorl 7y agoThe path integral formulation is the most prevalent and successful version of quantum physics (this is what you describe in the second half). Non locality is different; it supposes that there are hidden mechanisms we have not uncovered (and may but be able to uncover) instead which describes our world. It must be non local to get the observed experimental results. Non local means data about the universe is teleporting faster than (conventional) causality allows i.e. the speed of light
- longtom 7y agoEither case seems to require faster-than-light or instant communication between alternative paths that are being tried out, so the distinction is whether the combination of different paths is mediated by another faster-than-light (non-local) particle or whether the combination is axiomatic to the laws of the universe without a particle mediating it?
- Misdicorl 7y agoNo, the path integral formulation does not require faster than light communication. Time is an explicit parameter
- chews 7y agoImagine entangled data transmission... having a matrix of entangled particles, using known truths to illuminate what has up until now have been unknowable things. Wow, it’s an amazing time to be alive.
- Zenst 7y ago"The experiment can be further extended to a larger scale using photons from distant stars and open a new route to quantum optics experiments at an astronomical scale." This would be interesting as a distant star would exhibit red-shift unlike something as close as our sun. So until further data such as this, we just have the single experiment. Which from my limited understanding, would give the data to draw some solid conclusions. Exciting stuff, and I could only speculate upon the results, though somebody more up upon the matter may well have some better insights. Though it may well be a way to measure distances more accurately would be my limited take away from this. Maybe not, but certainly something going on here that will enhance our understanding of physics on all levels.
- wwarner 7y agopdf of paper https://arxiv.org/pdf/1905.02868 https://arxiv.org/pdf/1905.02868
- nayuki 7y ago150 million kilometers = 150 gigameters
- wwarner 7y agoAn ars-technica writeup of the original paper: https://arstechnica.com/science/2019/08/identical-photons-generated-150-million-kilometers-apart/ https://arstechnica.com/science/2019/08/identical-photons-ge...