
Complex quantum teleportation achieved for the first time - lelf
https://phys.org/news/2019-08-complex-quantum-teleportation.html
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krapp
On why "quantum teleportation" can't be used for faster-than-light
communication:

[https://physics.stackexchange.com/questions/155913/quantum-t...](https://physics.stackexchange.com/questions/155913/quantum-
teleportation-and-no-communication-theorem)

[https://www.askamathematician.com/2013/01/q-what-is-
quantum-...](https://www.askamathematician.com/2013/01/q-what-is-quantum-
teleportation-why-cant-we-use-it-to-communicate-faster-than-light/)

[https://medium.com/starts-with-a-bang/ask-ethan-can-we-
use-q...](https://medium.com/starts-with-a-bang/ask-ethan-can-we-use-quantum-
entanglement-to-communicate-faster-than-light-e0d7097c0322)

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gibspaulding
What sort of technologies _could_ (theoretically) be built relying on "quantum
teleportation"?

~~~
anchpop
Uninterceptible communication would be one application

~~~
ptttr
> With this, the international research team has also made an important step
> towards practical applications such as a future quantum internet, since
> high-dimensional quantum systems can transport larger amounts of information
> than qubits. "This result could help to connect quantum computers with
> information capacities beyond qubits", says Anton Zeilinger, quantum
> physicist at the Austrian Academy of Sciences and the University of Vienna,
> about the innovative potential of the new method.

I wonder how a quantum internet would be different than the binary one.

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lota-putty
1\. Size of the Particle teleported?

2\. Displacement distance & velocity?

3\. Energy consumed?

Edit:

4\. Is it really a teleportation?

~~~
nine_k
«Austrian and Chinese scientists have succeeded in teleporting three-
dimensional _quantum states_ for the first time»

So, no particles were moved, it's just cloning the state of one particle to
another. It's also important, but it's not something like the "beam me up"
type of teleportation.

~~~
antisemiotic
This is exactly what " _quantum_ teleportation" means and it has never meant
anything else. "Beam me up" is pure fantasy.

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ackbar03
This reminds me of the ansible machine in Orson Scott cards Enders Game.

~~~
SomeOtherThrow
I highly recommend discussion of the development of the ansible in Ursula K.
Le Guin's _The Disposessed_ as well, although she makes it pretty clear that
there's a different theoretical basis for it ("simultaneity theory") than the
one Card uses.

~~~
anchpop
Does it address what would happen if I, relative to your reference frame, got
in my spaceship, accelerated to .5c and tried to talk to you over my ansible?
From my perspective, you're traveling slowly in time, but from your
perspective, I'm traveling slowly in time, so who's voice would sound slowed
down?

~~~
SomeOtherThrow
I don't remember if the interface was realtime or async off the top of my
head, but it would strike me as uncharacteristic of her (and strange in the
context of the plot) to not take that into account.

I'm not even sure if the ansible interface is actually described anywhere in
that book....

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viach
Interesting, is this teleportation thing restricted only by space or particles
can also be tangled being in different time periods?

~~~
TheRealPomax
It's only _called_ teleportation, it has nothing to do with teleporting matter
in the sci-fi sense.

Quantum teleportation is about preparing two particles so that that by
destroying the original particle's state by measuring it, and then
transmitting a specific bit pattern as regular information, constrained by the
speed of light, the other particle can be made to have the identical quantum
state as was measured on the now destroyed particle.

The quantum state is (destructively) "teleported" from one particle onto
another (preallocated) particle, obeying the rather mundane rules of classical
physics.

~~~
logicprog
In theory, could that be used on a block of random matter and a, say, banana,
so that you can get lightspeed transmission of banana-ness?

~~~
TheRealPomax
Realistic theory? No, not even remotely.

The problem comes from having to measure the quantum state of every quantum
particle in that banana and transmitting the bits necessary to perform the
state transfer. We're talking destructively reading out well over 10^25
particles, turning that into tens of yottabytes of data, and then transmitting
that data with error correction over distances that you can't just... you
know... ship a banana over.

And then you'd have to receive that data in a way that either lets you perform
the transfer in real time, or in a way that lets you store that data so you
can transfer the quantum states one by one or in small batches.

And that's if you're okay with "Scanning" the original banana in a way that
destroys the banana as yous scan it. Not the quantum states, the actual
banana: the destructive read of particles will cause nuclear reactions and so
very quickly you're no longer scanning "a banana" but "messed up subatomic
partilces".

~~~
DaiPlusPlus
I don’t like the term “observer” because it implies it’s an entirely passive
thing.

Why is it that we cannot passively observe quantum states? Why does
observation necessarily have to be destructive?

~~~
TheRealPomax
There is no such thing as "passive" observation: something has to change in
order for information to become known. Without a transfer of energy, no
observation can be made, so either we absorb the particle to register that
energy (and then it is literally gone after measurement) or we stimulate the
particle into emission (drastically changing its quantum state), or we "poke"
the particle by throwing things at it (changing its quantum state in the
process).

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atrandom
how did they get from this to quantum internet in once sentence?

~~~
ahelwer
In contrast to conventional internet where classical 1s and 0s are transmitted
via some medium like copper or fiber optics or radio waves, qbit states are
far too fragile to survive such transportation and so would be transmitted via
the quantum teleportation protocol.

Physical networking infrastructure will still be necessary; teleporting a qbit
requires a pre-existing entangled qbit pair in addition to two bits of
classical information, so you'll need some method of sending one half of an
entangled qbit pair to the recipient. It's okay if this process is lossy,
because you can easily generate & re-send an entangled qbit if it gets lost.
Once you successfully manage to get the entangled qbit through, you can use it
to teleport the qbit you actually want to send (whose state is presumably the
product of some long, expensive computation and therefore far too valuable to
risk sending via such a lossy channel).

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Jeff_Brown
In a nutshell, why are we trying to do this?

~~~
tunesmith
maybe... ultra-secure communication of very large data?

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AlexDragusin
First known teleportation device was called the Fax which brings us to the
reality that teleportation can be achieved by transferring the information
through space rather than translation through space as most people imagine it.

This, once reality (at human scale), will bring an important ethical dilemma
since for a short time there will be 2 of the same person, which for all
intents and purposes are the same, even more so than cloning. Obviously, after
transfer is complete, the source would have to be killed.

For non organic matter this could be great and perhaps the basis of some sort
of matter to energy converter (it takes energy to create the duplicate), in
time, storing the information of stuff you have transferred in a database can
do without the initial step, and simply recreate the stuff.

As with any tech, there is a double edge sword to be mindful of.

Be careful what you wish for then push that _teleport_ button as needed.

