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Scientists Achieve Direct Counterfactual Quantum Communication For The First Time (sciencealert.com)
schwit1 shares an article from ScienceAlert:
Quantum communication is a strange beast, but one of the weirdest proposed forms of it is called counterfactual communication -- a type of quantum communication where no particles travel between two recipients. Theoretical physicists have long proposed that such a form of communication would be possible, but now, for the first time, researchers have been able to experimentally achieve it -- transferring a black and white bitmap image from one location to another without sending any physical particles... It works based on the fact that, in the quantum world, all light particles can be fully described by wave functions, rather than as particles. So by embedding messages in light the researchers were able to transmit this message without ever directly sending a particle.
It's different than quantum entanglement (which Einstein described as "spooky action at a distance.") The article describes it as "a pretty cool demonstration of just how bizarre and unexplored the quantum world is."
It's different than quantum entanglement (which Einstein described as "spooky action at a distance.") The article describes it as "a pretty cool demonstration of just how bizarre and unexplored the quantum world is."
Oh please! We've been doing that since the invention of marriage, no wait, I mean politics...
“He’s not deformed, he’s just drunk!”
How is this different than radio?
If I'm 11000 miles from someone's radio transmitter, waves of magnetism induce electron movement in my local loop antenna (this description applies only to loop antennas.) The only particles -- electrons -- I'm dealing with are local. The particle movement is not induced by electrons that travelled from the source to my antenna. Magnetism isn't carried by particles. Right? Because it goes right through non-ferrous solid objects.
Light is just radio at a really high frequency, as far I understand it. Which may not be all that far. :)
Anyway, shine a light, induce particle movement at the receiver by detecting the waves...
Sounds like radio. What am I missing? There must be something, or this wouldn't be news.
--[not a physicist]
I've fallen off your lawn, and I can't get up.
Note that this does not allow for any form of FTL signaling. The No Communication Theorem https://en.wikipedia.org/wiki/No-communication_theorem is not violated.
Given the universally observable incompetence, the simulation environment running this universe is probably running on something in the same class as Windows XP. Create too many exceptions like the one in this experiment (ordinary things are clearly not simulated at this detail...) and you may just crash the whole thing. That may be bad.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
You can define a particle as something that has energy - either rest energy as mass, or energy in motion as a photon.
Most of the time you need some sort of transfer of energy to transfer information. A photon is sent from one place to another, it interacts with a sensor, and information is exchanged.
One interpretation of this effect is that the photon itself doesn't travel down the path, it's the *probability* of the photon that travels down the path. When a particle is emitted, the universe takes the particle and puts it on a shelf somewhere (outside the universe) and sends out an instantaneous probability wave. As the wave evolves, the universe checks it for interactions with things along the path, and when the probability indicates an interaction it replaces the probability wave with the particle.
The probability wave takes all possible paths from the source to the destination, including non-straight paths. Most of the time most of the paths cancel out, leaving one path (the straight line) or two (beamsplitter mirror) or a few more, depending on the configuration.
I haven't found a non-paywalled version of the frikkin' paper yet, so I can't comment on what they're doing, but it seems like they are using the probability that the particle might be at the destination to affect particles at the destination without actually sending the particle.
There was an article in Scientific American that talked about taking a picture of Medusa without receiving any photons from Medusa. The presence of a photon in a cavity will alter the resonance frequency of a cavity which can be detected (IIRC - the article was many years ago).
If what the paper claims is true(*), it means that information can be transferred from one location to another without the transfer of energy, which is a very interesting philosophical statement.
(*) Many times in physics, especially QM, experimental outcomes turn out to be different than expected, so it's good to do the experiments. (Viz. Popper's experiment.)
Does it require one? Or can I use it to get internet on my submarine?
Strange things are afoot at the Circle-K.
How is this any different from modulating the light with e.g. coloured filters to send signals?
It seems to me people have already been doing this for centuries.
"artefacts that couldn't surprise direct light shined on them."
Some needs to be severely reprimanded for this.
I've found the paper.
Using beamsplitters, Alice sets up one probability path that goes out to Bob and back. Bob can either insert a mirror, reflecting the probability path back to Alice, or not, making the probability path end there. Bob's mirror will change the phase of the Alice's photon in a way that can be detected by Alice, even though the photon doesn't actually go out to Bob.
A good simple example of what they're doing is the quantum bomb detector, where you can determine whether a bomb attached to a single-photon detector would explode if given a photon... without actually giving it a photon.
In the bomb example, you are getting information about the bomb without actually transferring energy to or from the bomb.
The experiment in the paper is somewhat similar.
https://sci-hub.cc/10.1073/pnas.1614560114
i think it's the one, took 1 minute to find its DOI and look that up on scihub
How is this any different from modulating the light with e.g. coloured filters to send signals?
It seems to me people have already been doing this for centuries.
it's exactly like modulating light using coloured filters.
Except that there is no light.
https://sci-hub.cc/10.1073/pnas.1614560114
i think it's the one, took 1 minute to find its DOI and look that up on scihub
1) I took more than 1 minute to look for other versions first, out of respect for SciHub. SciHub is a great resource, and I don't like to use their resources if it can be avoided.
2) I didn't post the SciHub link, out of respect for SciHub. SciHub is a great resource, and I don't want to use up their resources by publicly posting their links.
3) Pointing out things obvious to you in a snarky way is elitist.
4) Nothing is easier and more pathetic than being a critic.
The article is woefully short on details. What, exactly, do the senders of a message do, in this case?
And what is a "quantum channel"?
systemd is Roko's Basilisk.
Is there any idea why Lightspeed == Radio speed ?
Yes, it's because radio is light.
systemd is Roko's Basilisk.
Only if you don't open it.
Faster! Faster! Faster would be better!
Quantumpornhub.com is still being set up.
An antenna is not a lantern.
An antenna is the filament of a radio lightbulb.
I get what you're trying to say, but that's an oversimplification. The word light does not mean "anything in the entire electromagnetic spectrum" by any standard definition.
Lightspeed == radio speed because they are both forms of electromagnetic radiation (which travels at the speed of light).
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson
"The basic idea is this - someone wants to send an image to Alice using only light (which acts as a wave, not a particle, in the quantum realm)."
Nonsense. Photons have properties of both.
https://en.wikipedia.org/wiki/...
"researchers have been able to experimentally achieve it - transferring a black and white bitmap image from one location to another without sending any physical particles."
If you pretend a photon is only a particle which it is not then you can make pretend statements such as the above. And in a counterfactual pretend universe you would be right.
While being neither.
I can't decide whether the summary is wrong or just incomprehensible. I think it's wrong. Of course, it *may* be accurately reporting on the original article... but skimming the article I think that it's (the linked article) incomprehensible rather than just wrong. (It may also be wrong, but that's not something I can check.)
The article seems to imply that a quantum channel can transmit information without transmitting particles. (paraphrase "If the channel transmits a particle then it is discarded".) This seems wrong to me, but it's well out of my area of expertise.
I think we've pushed this "anyone can grow up to be president" thing too far.
Electrons don't move at the speed of light. They have mass (albeit quite a small, but non-zero, amount) therefore they can not move at light speed or they would have infinite mass (and take an infinite amount of energy to get up to speed).
Photons, not electrons, are the carrier of electromagnetic radiation. They move at the speed of light.
Antennas and lanterns both emit photons. Lanterns just happen to emit photons in a range of energy levels that our eyes are sensitive to. Antennas emit photons at a different wavelength that are picked up by long metal conductors, aka other antennas.
Specialist Mac support for creative pros, Melbourne
thing as all the "alternative factual" communications I've been seeing so much of recently?
It's both hardcore AND softcore, until you measure it.
Corruption is convincing someone that the selfless ideal is the same as their selfish ideal.
Radio utilizes an electron as the messenger particle.
It's helpful to stop reading the above comment at this point, and start watching out for all the electricity flying through the air into your radio.
Radio is electromagnetic radiation. So is light. Here's a handy chart
.
There are two basic ways to build yourself a radio antenna.
One responds to electrostatics; this, generally speaking, is electron, or photon activation - electrons in the antenna move because the applied charge across the antenna varies. This is ambient electron pressure varying as a function of the radio signal. This results in push-pull down the antenna cable, and it's amplified at the receiver, etc.
The other responds to magnetic fields. Not ambient electron pressure. A loop antenna is a classic example of that, and it's why I used it in my example.
Radio is an electro-magnetic phenomenon. EM for short. Electricity (electron flow and potential) is not the same as magnetism. Either one can induce the other. But they are not the same. And the claim that magnetism is photons... I just don't understand how that could describe reality. Unless photons ignore solid objects, and everything I've ever experienced (again, not a physicist or anything approaching one) tells me they don't. Electrons - photons in another life - stop at insulators. They don't transit them. Whereas magnetism is well known to do exactly that, and with zero trouble. Or so I conceived of it all until today.
So... the statement "magnetism is photons" makes no sense to me because radio goes right through very dense insulating materials, generally speaking. Materials that, for instance, the photons from my flashlight will not. Even if it's hella bright. Further, there is so little energy in radio waves that are nonetheless receivable, the idea of them (meaning photons) transiting a dense, thoroughly opaque substance with no particular attenuation is notionally counterintuitive to me. Which still doesn't mean it's wrong (see (a), below.) I can tell you for a fact that the magnetic component of radio waves do this, though. Which, it seems to me, implies that magnetic waves are not photons doing... well, whatever.
I have read all the answers and either (a) I am missing so much of the underlying physics information (most likely) that I cannot understand it, or (b) it hasn't actually been explained yet, or (c) the entire idea is somehow misdescribed so I *can't* understand it, but it's really something, just something else.
I've fallen off your lawn, and I can't get up.
https://www.quora.com/What-doe... Fixed, enjoy my Quoras
Maybe that someone else didn't mention Trump?
"Trump!!", the new Godwin.
I don't know whether you noticed, but those countries are becoming increasingly rare...
"Trump!!", the new Godwin.
Thank you. Although I have no great depth in the areas you're describing, you did provide a coherent framework that gives me some idea what might be happening. And you provided enough touchstones for me to fumble through learning more. Very much appreciated.
I got the idea that electrons = photons from camera sensor descriptions in the popular press. No doubt there was some level of error there, starting with me and possibly extending further. I've parked that idea. :)
Well, that's not really what I was saying; a loop antenna responds very little to electrostatic stimulus; this property makes it highly immune to local noise. Instead, it responds to the magnetic field, which tends to not be large in comparison for low energy local sources. Switching antenna types to a loop can and does result in noise levels dropping very significantly, and signals appearing that were previously completely buried in said noise. So both fields are there, but detecting the one doesn't have to involve detecting the other, and therefore the reception achieved can be said to be specifically of the magnetic component. Which I didn't understand to be composed of particles, as you have explained. Now that you have explained it, I understand the process to be an exchange of particles, and so that answers my original question - how is [idea in TFS] different than radio. Answer being, no particle exchange vs. particle exchange. That about sum it up?
I've fallen off your lawn, and I can't get up.
The Bat Signal.
As per de Broglieâ"Bohm pilot wave theory, changing the properties of the wave by modifying Bill's setup will have measurable effects on Alice's not outgoing particle :-)
It's so much simpler when you're using pilot wave theory. There's a particle and there's a wave. Literally.
There is no standard definition of the term, and if there was, Wikipedia would not be the definitive source for it. In fact, the Wikipedia page says this:
The word usually refers to visible light
In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not
systemd is Roko's Basilisk.
Electrons don't move at the speed of light.
True, but an electrical signal generally can travel a significant faction of c , with ladder line achieving 95-99% of c.
An imperfect model would be the same way sound can travel very quickly in a block of solid steel (~5700 m/s) while an individual atom of steel doesn't really move at all.
-- Sometimes you have to turn the lights off in order to see.
Yes, that's exactly my point. And any sampling of dictionary definitions will confirm this.
I would suggest this ubiquity constitutes a standard definition, at least in terms of commonly accepted usage.
And that's why I called your post an oversimplification, instead of incorrect. It is more accurate to say light and radio are both forms of EM radiation, than simply to state radio == light.
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson