Researchers quantum teleport particle of light six kilometres

Post by spacehome » Thu, Sep 22, 2016, 7:39 AM UTC

semi-extrinsic wrote: post #51

brazzledazzle wrote: post #42

Earlier quoted context omitted.

Is "measurement" or "observation" a simplified term for a complex process? It can't be as simple as a human "looking" at something since there's nothing special about humans (that I know of). I really wish I had the time and capability to understood how quantum entanglement really works. It seems a lot like magic if you take the layman explanations at face value.

This is a Hard Problem, to define what process is a "measurement" and what is not. But if we think about it very simply: a photon hitting a detector (or analog film strip) can be a measurement. Since this process converts quantum information to classical information (a digital or analog signal), we know that it must lose information. Only by making many measurements can we infer statistical properties of the entire q…

Post by spacehome » Thu, Sep 22, 2016, 8:38 AM UTC

ythl wrote: post #201

jdmichal wrote: post #28

I posted this in a duplicate thread: For those thinking that this is a step towards faster-than-light (FTL) communication: As far as I know it's fairly certain that quantum entanglement will not allow for FTL communication. Basic principle is that while measurements between both sides will be correlated, it's not possible to tell how they are correlated until both sides compare measurements. https://en.wikipedia.org/…

As far as I know, quantum entanglement is like two paper bags with two identical colored balls in them. You can separate the bags by a million miles, and yet if you look in one bag, you will know which color ball the other bag contains (because they contain the same color). Can someone correct this analogy if I'm wrong?

Post by 3chelon » Thu, Sep 22, 2016, 10:10 AM UTC

CocaKoala wrote: post #106

24gttghh wrote: post #102

Earlier quoted context omitted.

I believe Wolfgang Tittel was simply defining a picosecond for the readers of the article.

You're probably right. However, the article is written in a way which at the very least heavily implies something else. >“The challenge was to keep the photons’ arrival time synchronized to within 10 pico-seconds,” says Tittel. “That is one trillionth, or one millionth of one millionth of a second.”

Post by etatoby » Thu, Sep 22, 2016, 11:45 AM UTC

dave_sullivan wrote: post #197

johncolanduoni wrote: post #135

Earlier quoted context omitted.

You've compounded their lazy science reporting by making quite a few mistakes yourself in your description: 1. There is no duplication or copying of information, the original particle's state is destroyed. Copying is impossible when dealing with general quantum states[1]. (You may be thinking of measuring an entangled pair to randomly produce a stream of classical bits on each side that is the precise inverse of what…

It's still the consensus that we can't (even theoretically) send a bit of information this way, right? Like, no quantum telegraph? So we measure the particles and find that they are in inverse states. I assume there's a reason for this, but why are we sure that we're not just reading off a random number generator that's set from the same seed?

Post by sebringj » Mon, Sep 26, 2016, 8:34 PM UTC

jomamaxx wrote: post #132

sebringj wrote: post #110

Does modifying the state of one entangled particle then destroy the link between them? If it does, then how can you continually communicate without distance being a factor as you'll have to resupply? I hope it doesn't or there is some work around or I simply am completely asking the wrong question.

Yes, the observation destroys the entanglement. The communication does not really happen between the state that is 'teleported' - you still have to manually send the photons 6km or whatever. But - very crudely - you can pass information from one entangled particle to it's pair 6km away and observe the results. So, you still have to have a fiber or whatever. Also - because it's all probabilistic and you don't know for…