[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)