Researchers quantum teleport particle of light six kilometres • Hacker News Board

Re: Researchers quantum teleport particle of light six kilometres

#101

Post by moefh » Wed, Sep 21, 2016, 5:33 PM UTC

javajosh wrote: post #92

semi-extrinsic wrote: post #51

Earlier quoted context omitted.

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…

> 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 quantum state. This is exactly what happens with the two-slit experiment. Wow, I've never heard it explained that way. That's brilliant - did you come up with it? Interference patterns are the…

> Interference patterns are the result of a huge number of individual photons interfering with each other

It's stranger than that. A single photon can interfere with itself, see for example: https://en.wikipedia.org/wiki/Double-slit_experiment#Interfe...

Re: Researchers quantum teleport particle of light six kilometres

#102

Post by 24gttghh » Wed, Sep 21, 2016, 5:35 PM UTC

CocaKoala wrote: post #91

hartator wrote: post #75

Earlier quoted context omitted.

Is it not? https://en.wikipedia.org/wiki/Picosecond "or one millionth of one millionth of a second"

Your link says that one picosecond is one millionth of one millionth of a second. The article itself says (or at least is written to imply) that ten picoseconds is one millionth of one millionth of a second. Since ten is not one, one of those two statements (and definitely not ten of those two statements) must be incorrect.

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

Re: Researchers quantum teleport particle of light six kilometres

#103

Post by stephengillie » Wed, Sep 21, 2016, 5:35 PM UTC

TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

This is, very confusingly, "teleportation of the quantum state". Not unlike how merging a pull request is "teleporting the software state of your repo", but instantaneously. Essentially this is just entanglement at 6 kilometers, described by a blustery article.

Re: Researchers quantum teleport particle of light six kilometres

#104

Post by drostie » Wed, Sep 21, 2016, 5:36 PM UTC

javajosh wrote: post #92

semi-extrinsic wrote: post #51

Earlier quoted context omitted.

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…

> 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 quantum state. This is exactly what happens with the two-slit experiment. Wow, I've never heard it explained that way. That's brilliant - did you come up with it? Interference patterns are the…

Are you still comfortable with this explanation if the photons are released with a 1-second gap between them and the tally is visibly shown building up into the interference effect on a computer screen? "Interfering with each other at an enormous rate" might mislead you a bit; neither "each other" nor "enormous rate" is particularly important in the double-slit interference pattern.

Re: Researchers quantum teleport particle of light six kilometres

#105

Post by semi-extrinsic » Wed, Sep 21, 2016, 5:36 PM UTC

javajosh wrote: post #92

semi-extrinsic wrote: post #51

Earlier quoted context omitted.

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…

> 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 quantum state. This is exactly what happens with the two-slit experiment. Wow, I've never heard it explained that way. That's brilliant - did you come up with it? Interference patterns are the…

I can't say I can claim any credit for the idea, no, this is what is you learn once you chase the QM rabbit hole deep enough. But it's maybe not a common explanation in Intro to QM class or in popular science writing?

Actually (technical nitpick) it's even more lovely than what you describe: people have done the two slit experiment with verifiably single-photon sources... and you still get interference patterns. Really, we know that only a single photon exists between source and detector for the entire lifetime of the photon, and yet you get interference. The only explanation is that it interferes with itself, which is what QM says happens.

The original "Wow! QM!" two slit experiments were done with electrons, which were thought of as competely particle-like, whereas light was thought of as completely wave-light. QM of course says both are both.

Re: Researchers quantum teleport particle of light six kilometres

#106

Post by CocaKoala » Wed, Sep 21, 2016, 5:38 PM UTC

24gttghh wrote: post #102

CocaKoala wrote: post #91

Earlier quoted context omitted.

Your link says that one picosecond is one millionth of one millionth of a second. The article itself says (or at least is written to imply) that ten picoseconds is one millionth of one millionth of a second. Since ten is not one, one of those two statements (and definitely not ten of those two statements) must be incorrect.

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.”

Re: Researchers quantum teleport particle of light six kilometres

#107

Post by [deleted] » Wed, Sep 21, 2016, 5:43 PM UTC

TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

[deleted]

Re: Researchers quantum teleport particle of light six kilometres

#108

Post by fitchjo » Wed, Sep 21, 2016, 5:43 PM UTC

booleandilemma wrote: post #53

Rooster61 wrote: post #7

Earlier quoted context omitted.

True, but that doesn't mean you can use words that fundamentally change the meaning of the sentence and then pass it off as the same thing.

For all intensive purposes

I (hopefully) see what you did there :)

Re: Researchers quantum teleport particle of light six kilometres

#109

Post by raverbashing » Wed, Sep 21, 2016, 5:44 PM UTC

duaneb wrote: post #99

TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

At the subatomic level, is there any real difference between information and a "thing"? Seems mostly philosophical and arbitrary at that point.

What do you mean by that?

Re: Researchers quantum teleport particle of light six kilometres

#110

Post by sebringj » Wed, Sep 21, 2016, 5:49 PM UTC

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.