[HN Gopher] Undetectable quantum computation and communication f...
___________________________________________________________________
Undetectable quantum computation and communication for alien
civilizations
Author : mathgenius
Score : 112 points
Date : 2021-07-29 15:50 UTC (7 hours ago)
(HTM) web link (arxiv.org)
(TXT) w3m dump (arxiv.org)
| BigProofOfStake wrote:
| Sounds like someone just wrapped up their reading of The Three
| Body Problem series.
| ctoth wrote:
| Terry Rudolph's[0] 132 research works with 7384 citations and
| 7159 reads, including: Creation of Entangled Photonic States
| Using Linear Optics[1].
|
| Or yeah, maybe he just finished Remembrance of Earth's Past
|
| [0]: https://en.wikipedia.org/wiki/Terry_Rudolph
|
| [1]: https://www.researchgate.net/scientific-
| contributions/Terry-...
| gus_massa wrote:
| > _The distributed computation requires classical communication
| between receivers, however, similar to standard measurement-based
| computation, that communication is of purely random outcomes and
| so can be indistinguishable from noise._
|
| The main problem of this idea is that you _also_ need a classical
| channel to transmit the information. You can use natural sources
| of entangled photons as proposed[1], but you will need a classic
| channel that can be detected. In the classic channel you will see
| a random stream of data, so it will be impossible to decode, but
| you can still see that there is some communication.
|
| [1] I think it's not so easy, but let's ignore this second
| objection.
| yourenotsmart wrote:
| Our own encrypted communication is indistinguishable from
| noise, save for the initial handshake, which represents a
| detectable pattern, but mostly because we happen to already
| have the full specification of the protocol handy.
|
| Additionally, entanglement can't be used for FTL communication,
| classical channel or not. So this, combined with the fact you
| don't need any quantum level mechanics for hidden communication
| that looks like noise... I'm unsure what the author is
| proposing and where that idea came to them.
| thereddaikon wrote:
| That's definitely untrue. You can fire up an SDR and easily
| pickup encrypted radios from businesses and public safety.
| You can even classify the protocol they are using, P25, DMR
| etc based on the characteristics of the signals. They are
| definitely not indistinguishable from noise.
|
| Low Probability of Intercept radios can be harder to pick up
| because they use various techniques like frequency hopping
| but even then they don't blend in to the background.
| yourenotsmart wrote:
| Knowing the popular protocols is an advantage you wouldn't
| have with "alien communication". Encryption in general
| doesn't try to hide itself, it just tries to hide the
| payload, so things like packet/frame structure, headers,
| handshake and so on can be relatively easy to pick up,
| because they're not hidden in the first place.
|
| Consider how unsophisticated the Enigma machine looks to
| modern eyes. Now throw some modern encrypted traffic back
| at them, would they even understand there's signal in
| there? Unlikely.
|
| Those are just few decades of difference on the same
| species with the same tech history.
| zardo wrote:
| > Now throw some modern encrypted traffic back at them,
| would they even understand there's signal in there?
|
| Definitely yeah
| yourenotsmart wrote:
| Well if all we need is just some bald confidence, I'll
| respond with a "Definitely nope".
| unparagoned wrote:
| Well I can confidently say you are wrong
| yourenotsmart wrote:
| I can confidently say 2+2 is 5
| sparrigan wrote:
| The paper addresses this specifically - the information is
| indistinguishable from thermal noise.
| duncan-donuts wrote:
| Looking forward to the ELI5 version of this. It sounds
| interesting but I have no idea what they're saying.
| kinghtown wrote:
| that's because it's undetectable. no one knows what they are
| saying.
| pugworthy wrote:
| I believe the parent meant he doesn't know what the paper is
| saying, not what the aliens might be saying.
| yourenotsmart wrote:
| It seems like a wild and possibly inaccurate speculation on the
| use of quantum effects for communication.
|
| Before we start speculating how aliens communicate, we need to
| have some idea how WE can communicate via the same means, even
| in a most crude way (like sending one bit of information few
| feet away). Otherwise saying "well aliens maybe know more so
| maybe they can do it" could be used to submit a paper about
| just anything at all we fancy. Say time machines.
|
| So far, measuring the properties of entangled particles has not
| been demonstrated as capable of transferring information faster
| than light. You can only do the math and conclude what happened
| when you have BOTH RESULTS. And to have both results, you need
| to communicate them via traditional means, like giving the
| other team a phone call, or, you know, walking there and asking
| them.
| mrkramer wrote:
| This reminds me of Quantum Cryptography in which Conjugate Coding
| [1] is used. Conjugate Coding is " A method of transmitting
| multiple messages in such a way that reading one destroys the
| others. This is called quantum multiplexing and it uses photons
| polarized in conjugate bases as "qubits" to pass information."
|
| Even if you can detect such communication it is hard to eavesdrop
| it because:
|
| "Quantum cryptographic systems take advantage of Heisenberg's
| uncertainty principle, according to which measuring a quantum
| system in general disturbs it and yields incomplete information
| about its state before the measurement. Eavesdropping on a
| quantum communication channel therefore causes an unavoidable
| disturbance, alerting the legitimate users." [2]
|
| [1] https://en.wikipedia.org/wiki/Conjugate_coding
|
| [2] https://www.cs.mcgill.ca/~crepeau/CRYPTO/Biblio-QC.html
| max_ wrote:
| Interesting.
|
| Is there a way you could implement this phenomenon in
| software/hardware and use it as a next secure channel for
| communication?
| [deleted]
| go_elmo wrote:
| Since it is no inherently present physical fact in classical
| systems, it will have to fight with classical problems (bugs
| / backdoors etc) which would throw you back to classical
| encryption for security
| suifbwish wrote:
| Quantum communication requires a continually renewed source of
| mutually shared entangled pairs to send communication. When
| entangled states collapse, which they must do in order to send
| information, the particle pairs are no longer entangled and can
| thus no longer send information. These civilizations would have
| to find a way to keep a stable quantum pairing which can be
| observed without collapsing the quantum state, which is the
| equivalent of finding a way to stop black holes from emitting
| Hawking radiation; essentially they would need to find a way to
| stop entropy as we know it in order to make long distance quantum
| communication sustainable.
| trutannus wrote:
| > These advanced civilizations would require technology I can't
| think of how to implement
|
| I mean, that's part of what makes them advanced civilizations.
| mrfusion wrote:
| Place a beam splitter between you and fire a laser. Get
| entangled particles back.
|
| Or place an entangled particle emitter between you
| throw1234651234 wrote:
| I don't get it - wasn't it concluded that instantaneous
| communication is impossible, aka you can't transmit information
| EVEN if you were to take a decade to move two entangled
| particles apart, all you would get is data from 10 years ago?
| grepfru_it wrote:
| FTL communication is not possible. You have access to the
| entangled particle right now but, to send information, you
| are bound to the limits of the classical channel (the 10 year
| problem transmitting information about the entanglement)
| Moodles wrote:
| Is it really "equivalent"? I get both problems are about
| entropy in the universe but I would have thought managing the
| state of a black is harder, due to its suction into oblivion
| and whatnot.
|
| I don't know much about if it's possible to make entangled
| particles stable somehow, or whether you could maybe just have
| a lot of them so you never run out even if a lot become
| untangled naturally. Doesn't quantum key exchange use entangled
| particles? So it must be possible to keep them stable for at
| least a little while.
| godelski wrote:
| The author uses the first person plural, I suggest he adds his
| cat as a co-author[0]
|
| [0] https://en.wikipedia.org/wiki/F._D._C._Willard
| kook_throwaway wrote:
| I love that the "See Also" section links to this "list of
| animals with fraudulent diplomas"
| https://en.m.wikipedia.org/wiki/List_of_animals_awarded_huma...
| soheil wrote:
| > Entanglement, in our experience, only manifests itself when
| the cleverest of our species capture and protect it
| appropriately in controlled and delicate experiments.
|
| He definitely comes off as slightly off-putting.
| 5cott0 wrote:
| Do not answer! Do not answer! Do not answer!
| par wrote:
| i dont know what any of this means, but it was some of the
| coolest sounding sentences i've read in a while.
___________________________________________________________________
(page generated 2021-07-29 23:00 UTC)