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Researchers Demonstrate Teleportation Using On-Demand Photons From Quantum Dots (phys.org)
An anonymous reader quotes a report from Phys.Org: A team of researchers from Austria, Italy and Sweden has successfully demonstrated teleportation using on-demand photons from quantum dots. In their paper published in the journal Science Advances, the group explains how they accomplished this feat and how it applies to future quantum communications networks. Scientists and many others are very interested in developing truly quantum communications networks -- it is believed that such networks will be safe from hacking or eavesdropping due to their very nature. But, as the researchers with this new effort point out, there are still some problems standing in the way. One of these is the difficulty in amplifying quantum signals. One way to get around this problem, they note, is to generate photons on-demand as part of a quantum repeater -- this helps to effectively handle the high clock rates. In this new effort, they have done just that, using semiconductor quantum dots.
Prior work surrounding the possibility of using semiconductor quantum dots has shown that it is a feasible way to demonstrate teleportation, but only under certain conditions, none of which allowed for on-demand applications. Because of that, they have not been considered a push-button technology. In this new effort, the researchers overcame this problem by creating quantum dots that were highly symmetrical using an etching method to create the hole pairs in which the quantum dots develop. The process they used was called a XX (biexciton)--X (exciton) cascade. They then employed a dual-pulsed excitation scheme to populate the desired XX state (after two pairs shed photons, they retained their entanglement). Doing so allowed for the production of on-demand single photons suitable for use in teleportation. The dual pulsed excitation scheme was critical to the process, the team notes, because it minimized re-excitation.
Prior work surrounding the possibility of using semiconductor quantum dots has shown that it is a feasible way to demonstrate teleportation, but only under certain conditions, none of which allowed for on-demand applications. Because of that, they have not been considered a push-button technology. In this new effort, the researchers overcame this problem by creating quantum dots that were highly symmetrical using an etching method to create the hole pairs in which the quantum dots develop. The process they used was called a XX (biexciton)--X (exciton) cascade. They then employed a dual-pulsed excitation scheme to populate the desired XX state (after two pairs shed photons, they retained their entanglement). Doing so allowed for the production of on-demand single photons suitable for use in teleportation. The dual pulsed excitation scheme was critical to the process, the team notes, because it minimized re-excitation.
I understand some of those words!
Does this mean we can have a 0 latency network connection regardless of distance some day?
Then we'll never have it... I kid I kid... When do we get the countertop unit?
“He’s not deformed, he’s just drunk!”
The rule you may know as "nothing can go faster than light" is actually "information can't be transmitted at more than light speed". You can find ways of measuring "speed" that come out to a value greater than C, but in no case do those allow one to transmit information from here to there at a velocity greater than C. At least not if "here" and "there" are more than an atom apart.
In quantum theory specifically, there's something called the no-communication theorem.
One example of a tease is that it's believed using quantum entanglement, two observers at a distance can see the same effect at exactly the same time - as if they both had access to the two ends of a very long string (or cat), and both ends of the string do the same thing at the same time. However, neither end can *effect* the behavior, so they can't send information.
There are a lot of ways to get excited *thinking* something implies faster than light communication if you understand a little bit of quantum physics.
What?
I thought the point of entanglement was that they still danced the same tune over infinite distance.
A team of researchers from Austria, Italy and Sweden has successfully demonstrated teleportation using on-demand photons from quantum dots
What I'm pretty sure this means, is that you can have one place on earth that generates a huge quantity of light, and instead of buying lightbulbs we can all just buy varying clusters of quantum dots for light that just emit the results from the singular source, no matter how far! Pretty awesome.
Imagine clothes with quantum dots embedded. Luminous!
No need to wonder if that quantum dot in the fridge is off or on. It is light, eternal!
And screw headlights on cars, we are making the WHOLE ROAD out of glowing quantum dots!
Just make sure no-one hits that master off switch... hoo-boy!!
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Soon I'll be able to walk into my quantum-dot TV and be teleported to another world. Persona 4 predicted this!
Corruption is convincing someone that the selfless ideal is the same as their selfish ideal.
Picking through the twaddle:
"The two consecutive XX photons are sent directly to an APD connected to the correlation electronics."
There's the filter again, so these properties are the same at a given time...
"The two consecutive X photons are instead launched to an unbalanced Mach-Zehnder interferometer necessary to overlap them at BS2, which is used for the Bell state measurement. "
And there's the test done *after* the filter again. Oh boy, you always see this.
"For clarity, Fig. 1D shows only the configuration in which the early photon (XE) takes the long path, while the late photon (XL) takes the short path. In this case, the two X photons arrive at the same time at BS2 required for the quantum interference. "
Holy fuck, if only you'd stop your quantum bullshittery for a second, you've already proved the very thing I'm asking you to prove.!
This here, the second part:
https://science.slashdot.org/comments.pl?sid=13041516&cid=57791044
It's RESONANCE, not only is the photon 'entangled' with the t=0 spins, it's also in the same state for t=1 spin, t = 2 spins.... presumably your path length difference is a multiple of W,.... (W ~ approximately the size of the current proton)???
https://science.slashdot.org/comments.pl?sid=13041516&cid=57791044
"Entanglement Mk II:
You can extend the experiment to prove more:
1. Every 1F spin, the matter should be in the same state.
2. So if you can make an experiment that compares photons at T=0, against protons at T=1 spin, they will also be 'entangled'.
3. You would probably find it easier to work with W, the wavelength, which should be approximately the size of a current model of the proton (p*r*oton). The photon at X=0, should be 'entangled' with the one at X=W and X=2W, and X=3W..."
What's the different in path length, is it a multiple of the proton size???
http://advances.sciencemag.org/content/4/12/eaau1255
So you think you've teleported the state, when actually its a *repeating* state driven by the underlying resonance.
You've proved resonance, nearly. You just need to correlate W to times it repeats.
"it is believed that such networks will be safe from hacking or eavesdropping due to their very nature."
Well isn't that special! Truly private communication. But wait, isn't that against government policy? Don't our governments want access to all our communication, without the bother of encryption? Don't they want back doors to our devices?
But maybe, just maybe, there is an exception for our masters in government, in police work, for corporate boardrooms and financial wheeler-dealers such that they can have the privacy denied to common citizens.
...omphaloskepsis often...
Despite all the "teasing" that our science fiction provides, the laws of physics simply do not provide any way that we could build faster-than-light space ships. There will never be an intergalactic community. We are stuck on this rock until the Sun blows up, and that's it.
Yes it's true that things we have now were science fiction in the past. But they knew far little about physics than we know now. They didn't know what the boundaries were. And we have a very solid grasp of them now.
And those boundaries are damn stifling.
Can you also show that radio waves travel at (almost nearly) C, whereas Gamma rays travel slightly *slower* than C? It will be tiny, something like an order of 3 or 4 magnitudes less than C. It won't be much but it should be measurable?
This "all EM waves travel at C in a vacuum" thing, isn't true for these dipolar resonant systems.
On-demand photons...so, this is like quantum Uber? Does it use 3D-printed neural networks?
No flies are around
> and bullet proof against hacking the key generation.
Several times a year there's a new exploit against yet another "bullet proof" encryption method.
In theory, entanglement might make wiretapping harder. Once upon a time, fiber optic was impossible to wiretap. Now it's pretty easy.
There IS a single encryption method that has remained secure for thousands of years, but it's damn inconvenient.
Well, duh. There's no benefit being re-excited. Wait, what we were talking about?
CAPTCHA: dismount
The breaking of entanglement is faster-than-light information transmission and thus breaks general relativity.
Suppose Alice is on a space station around Jupiter, and holds one particle from an entangled pair.
Suppose Bob, stationed in a space station around Deneb, holds the other particle.
If the breaking of entanglement results in instant recognition of this breaking, then one can effectively send a signal to both Alice and Bob in faster-than-light speed!
So something is wrong in all this. Either general relativity is wrong or, more probably, entanglement is not faster-than-light!!!
So something is wrong in all this. Either general relativity is wrong or, more probably, entanglement is not faster-than-light!!!
General relativity never made any proclaims about entanglements.
So: why do yo think it is wrong? Which particle of light or energy or mass is transporting the information, which /. is full with ignorants trying to claim it is not the case. 50 or 60 years ago it was unthinkable you could transport information on that base. Sine 30 years we know: we can.
is bound to the speed of light? There is none, and as we already know that quantum state transfer is instantly (since 90 years or so) I really wonder why
How backyard are you actually?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
This doesn't appear to be teleportation, just the usual cherry picking with coincidence detectors.
I'm starting to suspect that no quantum teleportation has ever been performed, let alone in this experiment.
Do you guys really think any form of teleportation will ever see the light of day? i think not.
Just think if some sort of instant wireless communication was invented. How many companies would fold over night..
And if it was al of a sudden pissible to teleport yourself or goods. everything remoteley connected to transportation would collapse. Half the worlds poppulation would be without work over night. Goverments and countries would fall like a cardhouse.
What I'm pretty sure it means is that a third of Slashdot didn't read the article, a third can't read and a third think this is where you try out for the Morcambe and Wise show.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
No, it isn't FTL, because distance isn't absolute. If ER=EPR, the distance travelled must always be zero regardless of the distance seen by an external observer.
It isn't necessarily FTL regardless, as an entangled photon is in all states. You're simply collapsing the probability wave to one of those options.
The other particle is also in all possible states, so the state isn't transmitted. Probability waves aren't information and don't radiate, so don't travel.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
You aren't transporting information faster than light.
The entanglement breaks the moment you measure it. But you need to know to measure it or you are setting the state rather than reading it.
Now... There are experiments such as the delayed choice quantum eraser which show that the act of measurement can in fact induce an effect which is retrocausal in nature. But even with such experiments, there is no way of obtaining the information until it has been measured and the results of the measurement transfered at light speed to it's destination.
The property mentioned here is useful because it can demonstrate unequivocally that the information was untampered with. It's pretty simple.
Alice and bob create entangled photons, store the photons and separate them by a large distance.
Alice encodes information into her set of photons, then transmits the encoded data to Bob.
Bob can then measure his photons using the information he received from Alice and if it matches, then Bob knows for certain that the information has no been tampered with.
Thus making this more like a tamper proof seal than true encryption.
Other methods of quantum encryption rely primarily on this tamper-proof concept.
Instead of sending the entire plaintext in the clear and having Bob verify it.
Alice can instead encrypt the data using a pre-agreed algorithm, write the encrypted data to her photons then send the key to Bob via an out of band exchange. This can mean they exchange the key before hand and simply agree that after a fixed period of time, Bob will check his photons for a message and attempt to decrypt. Or alternatively they could use the photons to handle the handshake portion, effectively exchanging keys by querying and setting the photons at set intervals.
Because of monogamy of entanglement, if the connection is being intercepted, then decrypting the information will result in nothing but random noise.
In all cases, Bob doesn't get information if it's been tampered with, it's either all or nothing.
The real flaw here is the initial generation of photons. They can only generate so many photons while together. Once apart, they need to receive a stream of entangled photons in order to keep passing messages.
When they are close together they can share the same photon source and ensure it hasn't been tampered with. But once apart they have no way of knowing if the photon source itself has not been replaced with a man in the middle device. Generating 2 pairs of photons and sending one of each pair to each of Alice and Bob. Monogamy of entanglement does not help, because the source of photons is compromised. Therefore the further away they are from the photon source, they are, the less certain they can be about the new photons arriving.
What this article appears to be saying is that they can entangle 2 quantum dots to generate entangled pairs, thus keeping the photon source local.
If so, it's bloody amazing, but the distances here are miniscule, and I wonder if they can really keep the dots from decohering over long time & distance scales.
Suppose Bob, stationed in a space station around Deneb, holds the other particle.
If the breaking of entanglement results in instant recognition of this breaking, then one can effectively send a signal to both Alice and Bob in faster-than-light speed!
So something is wrong in all this. Either general relativity is wrong or, more probably, entanglement is not faster-than-light!!!
You can't predict how the wavefunction will collapse. Just that it will collapse in the same way on both ends.
You also can't "see the collapse" on the other end, you can only collapse your own end.
You can't use this to communicate.
Two Danish researchers exposes in a new book extensive faults and deficiencies in the PISA methodology and the use of statistics. https://clasofm.com/clash-of-c...
How much extra does this cost on your cable bill?
it is believed that such networks will be safe from hacking or eavesdropping due to their very nature
But Australia's government will still demand a backdoor...
My eyes reflect the stars and a smile lights up my face.
> Breaking of entanglement, or any other spooking behaviour of entanglement is "transmitted" instantly.
There is a relationship between the local qubit and the the distant qubit such that a change to one seems to cause one of several changes to the other.
Unfortunately, to measure the change and find out exactly what happened to the distant qubit, one requires two classical bits of information about the distant qubit. You can easily find the protocol via Google.
Being stuck here is all about mass conversion and exhaust velocity. In fact, the faster you go the less time it takes to get there.
Time Dilation wrt Space travel
Dilation Calculator
I think the biggest issue with interstellar space travel is collision with anything larger than a grain of sand.
So... is this teleportation or simultaneous photon shedding? The title caused some excitation, but upon reading it, I don't think I'll be having any re-excitation either.
Whenever a player quits EVE to go play WoW, the Average IQ of both games increase.
I agree that with what we know today, "the laws of physics simply do not provide any way that we could build faster-than-light space ships".
But what if our current knowledge prevents us from even observing FLT activity. Imagine just 200 years ago. It could have been argued that Europe could not communicate with the US any faster than it takes a person/pigeon/entity to travel that distance. At best, something could be extremely "loud" and shout across the ocean to relay information. The amount of energy/decibels to facilitate that would be both impractical and likely destructive to anything nearby. Introduce the telegraph and suddenly information could be communicated at light speed with relative easy and small power requirements. At that point in time though, communications like that would have been crazy science fiction and regarded as fantasy.
Today, to reach FTL travel it requires an infinate energy among with other engineering issues. I don't know if there is a similar solution to FTL travel/communications, but I can't 100% rule out that someone won't be able to figure out some "trick" in the next million years.
Ninjas don't carry tic tacs
If you shout into space and then race ahead of your shout and intercept it you will be able to communicate with yourself yesterday from tomorrow.
And? What exactly do you want to say? :D
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Quite simple: There is no way to detect entanglement has been broken. You can test one of the particles, but you can't tell whether this test broke the entanglement, or whether it had already been broken by a test of the other particle.