

Quantum teleportation achieved over record distances - ananyob
http://www.nature.com/news/quantum-teleportation-achieved-over-record-distances-1.11163

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jaekwon
If you can't retrieve the information "quantum teleported" until something
else bridges the gap afterwards, then how can you say that anything was
teleported at all?

There would have to be a qualitative or quantitative difference between what
was supposedly teleported and the "key" that must be transfered afterwards.
Either you can teleport a gigabyte of information and retrieve it with a
kilobyte key, or you can teleport a material thing with a "key" comprised of
less information needed to encode its molecular structure.

Otherwise, teleportation seems to be a misnomer.

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sp332
The point is that you can exactly recreate a particle including its entire
quantum wave function (preserving uncertainties) from one place to another
without "existing" in between. That's why it counts as teleportation: you get
the same object, not a similar object but _the same_ object all they way down
to quantum fluctuations, at a distance.

~~~
Symmetry
That actually isn't how this works. Yes, you do have two objects with
entangled wavefunctions but that isn't remarkable at all. And the entanglement
occurs when the objects are created at the same place, and then they proceed
to the measurement points using entirely conventional slower-than-light means.

Its only a single bit, the polarization of the photon, that is found to have
been determined in both places simultaneously. Its true that this is a new
piece of information that arises in both locations simultaneously, but since
this is a thing that appears in two places rather than something that moves
from place A to place B I'd argue that the term "teleportation" is pretty
misleading here. After the measurement the measured particle is hopelessly
entangled with the measurement apparatus and through that with the surrounding
universe, so the unique link between the two particle is hopelessly broken at
that point.

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sp332
_found to have been determined in both places simultaneously._

That's not true. You measure one of the qubits, and its state is destroyed,
randomly scrambled. When you transmit the information and apply it to the
other qubit, it now has the same polarization as the first one _had_ , before.
You still don't know what the polarization is though! The entanglement is
still intact, and you haven't made a measurement of the system (as a whole) so
the wavefunction has not collapsed.
<http://en.wikipedia.org/wiki/Quantum_teleportation#Remarks>

~~~
Symmetry
Oh, huh, the process described there is distinct from the sort of "Quantum
Teleportation" that I was used to. Using an entangled pair and some
transmission of classical bits to transmit a qubit across a distance is pretty
neat, and this "quantum teleportation" really is quantum teleportation. It's
only sort of related to the cryptogrpahic technique I'd previously heard
described as "quantum teleportation", but in the absence of evidence as to who
grabbed that pair of words first I won't complain.

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Mitt
Often “why”-questions are interpreted as criticism. I would like to ask one,
just because I am curious: why are people interested in this for
communication? With current technology we can communicate with within the
limits of the speed of light. We can also encrypt communication. So, what
makes this technology so interesting, that people may want to use it in the
future? Will it be cheaper? Faster? More secure/better encrypted?

~~~
thomaslangston
From the article:

Teleportation can also securely transmit quantum information even when Alice
does not know where Bob is. Bob can take his entangled particle wherever he
pleases, and Alice can broadcast her instructions for how to ungarble the
teleported state over whatever conventional channels — radio waves, the
Internet — she pleases. That information would be useless to an eavesdropper
without an entangled link to Alice.

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JeremyBanks
As far as I can tell, this just seems like an obscenely overcomplicated one
time pad. Instead of Alice giving Bob a string of bits that are known in
advance, she gives Bob an entangled particle that can be collapsed to
determine a string of bits at a later date. I can't see any security benefit.

This is very neat from a purely scientific perspective. It seems pointless and
misleading to try to present it as having direct practical value.

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jvdongen
For one thing, AFAIK, Alice can be sure that Bob's 'pad' is the only copy in
existence because no one can copy Bob's 'pad' without destroying the
entanglement.

For a 'regular' one time pad this is not the case. Someone could have copied
it and both Alice and Bob would be none the wiser until it's too late.

One-time pad based encryption schemes are theoretically unbreakable - one of
the things ( _the_ thing?) holding back wide spread adoption is the difficulty
of proper key management. This has the potential to solve that issue.

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zrgiu_
I know this is a long long time away but .. Could this be used to communicate
faster with stuff like the Curiosity rover ? I mean, once it becomes easier to
reproduce without big laboratories to actually read the quantum state of the
photons.

~~~
darkstalker
_And although part of the transfer happens instantaneously, the steps required
to read out the teleported quantum state ensure that no information can be
communicated faster than the speed of light._

Seems not.

~~~
pavel_lishin
It might increase bandwidth, though.

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RockofStrength
This phenomenon is explained by many-worlds: The two photons have both
polarization orientations in the multiverse. We are limited to a single
instance of the multiverse, and any interaction whatsoever between the photons
and our universe will force them into a single instance of polarization
orientation, as this is all we can experience, being interacting beings
ourselves.

Reality is really an immense interconnected binary tree, and we must always
travel along a single path. It has the property that reconciling paths (paths
that diverged but met up again with no interaction in our universe) will again
be accessible to us.

As Galileo was prosecuted for supporting Copernicus' heliocentric theory (more
specifically for championing reason over faith), the Church's default stance
was that the planets moved around the sky 'as if' they orbited the Sun. We are
in a similar position now with many-worlds vs. 'as if' many-worlds, based on
experimental evidence such as the Mach-Zehnder interferometer results.

~~~
jorangreef
Regarding: "As Galileo was prosecuted for supporting Copernicus' heliocentric
theory (more specifically for championing reason over faith)"

Nothing could be further from the truth. The first proponents of the
scientific method saw the process of describing the known universe as possible
only because of their faith in a rational Creator, their definition of the
word "faith" meaning "conviction backed by reason" (Hebrews 11). Their
hypothesis was that the creation of such a rational Creator would necessarily
be ordered, not chaotic as the pagans of the day believed, and that it would
be possible to seek to describe the creation in terms of scientific laws and
principles. By faith they understood that what is seen was not made out of
what was visible. This was the basis for the birth of the scientific method.

In the days of Galileo, the Church as you refer to, was nothing more than a
political militant state, opposed to the theology of the early Christians of
the 1st century, and opposed to the Scriptures which exposed its hegemony.
Indeed the Church would have mothers and fathers burnt at the stake for
teaching children the ten commandments and the Lord's prayer. People like
William Tyndale, and many other brilliant Oxford and Cambridge scholars were
hounded and martyred by the Church for translating the Bible into English and
circulating and discussing it in the 1500s.

While the Church may have opposed heliocentrism, Galileo defended
heliocentrism, and understood correctly that it was not contrary to the
Scriptures.

For people like Galileo and Kepler, faith and reason were the same thing. By
definition, it's impossible to have faith that is not based on reason, nor is
it possible to hold reason without faith. To do so is historical revisionism.
If you have a bone to pick with faith, then the best place to start is with
the life and death and resurrection of Christ in history. Did it happen? How
soon after the events were the eye witness accounts recorded? At what cost?
Independent? Do we read them as they were written? This is a matter of
historicity: did it happen? Not of philosophical possibility (naturalism), or
statistical possibility (frequentism).

~~~
calebmpeterson
Can you recommend any good literature discussing Galileo and Kepler and their
"faith and reason" view of the cosmos? I do not ask contentiously but with
genuine curiosity. In the (post) modern era there seems to be much noise about
faith (Christianity in particular) and science being irreconcilable.

What little I do know about many founders of the major fields of science seems
to indicate that the founding men and women saw no such dichotomy. Or at the
least were willing to struggle with the questions rather than throw the entire
matter out as "unscientific."

Lord Kelvin and Michael Faraday seem to have both Christians and creationists.
Newton was a Christian and claimed that "all my discoveries have been made in
answer to prayer." Joule (the unit's namesake) was at least a theist. Then we
have Louis Pasteur, Christopher Columbus, George Washington Carver, Samuel
Morse, and Blaise Pascal - each "men of faith."

Not that the above list should be taken as an argument by authority for faith.
Certainly not. However, it does leave me wondering how these great thinkers
saw the world so differently.

~~~
jorangreef
See:

David Seccombe, King of God's Kingdom, 280.

R. Hooykaas, Christian Faith and the Freedom of Science, 17. Encyclopedia
Brittanica article: Kepler, Johannes.

Further, it's interesting that Kepler was schooled by a protege of
Melanchthon, who was himself a key reformer with Luther and a contemporary of
Tyndale. These men, together with Erasmus, were of the finest minds of their
day, giants of the past, and giants still today.

"What little I do know about many founders of the major fields of science
seems to indicate that the founding men and women saw no such dichotomy."

Yes, certainly "blind faith" and science are irreconcilable. Blind faith is a
straw man. Men have wasted breath on it for years. Faith is quite different
from blind faith. The two (faith and blind faith) are equally irreconcilable.
Faith is simply acting today in the light of that which by reason one is fully
persuaded of. It need not surprise that great men of reason and action are
also men of deep, often Christian convictions about God.

"However, it does leave me wondering how these great thinkers saw the world so
differently."

As John Newton wrote, "I once was blind but now I see". As Philip said to
Nathanael, "come and see".

The Christian of the 1st century would convert from Judaism either after
seeing the risen Jesus, as at least five hundred on one occasion in Jerusalem
did at the time, or after hearing of him from those who had. Their witness, at
pain of death, was based on what they had seen and heard. Former persecutors
such as Saul of Tarsus, a protege of Gamaliel, converted after seeing the
risen Christ for themselves. [1][2][3][4]

It is notable that at least two members of the Jewish ruling council, which
tried Jesus, Nicodemus and Joseph of Arimathea, did not consent to the actions
of the council and followed Christ. These men had education and wealth. They
had access to Jesus and they believed, at great personal cost. Proclaiming a
crucified criminal as Sovereign King, "God with us", would have been
unthinkable for men such as these, were they not fully persuaded of God's
raising him up, and of the entirety of the Old Testament Scriptures, one
example being Isaiah 53, which pointed to a suffering and triumphant Messiah.
"Oh death, where is thy sting? Oh grave, where is thy victory?" To a
naturalistic worldview which claims the name of science whilst being far from
it, the gospel is hard to accept. Is it true? Did it happen? In our ignorance,
we think of God as silent, unyielding. God is not silent, he has spoken and
revealed himself in history. Those with ears to hear, let them hear.

Today we see the Lord through the eyes of history, through the accounts of
those who saw him. Our distance from the events need not be a hindrance, only
the distance of the accounts from the events, and that is, in terms of
history, a comparatively short span of only 20 to 60 years at most for the
various accounts, today collectively known as the New Testament, the letters
of Luke (a physician and meticulous historian in his own right by standards of
ancient history), Peter, Paul, John, Matthew, Mark, James and Jude (brothers
of Jesus) and outside of that, Tacitus, Suetonius, Josephus, Clement, Polycarp
etc.

Concerning textual criticism of the New Testament documents, see:

F.F. Bruce, various works. Paul Barnett, various works. Sir Frederic Kenyon,
director of the British Museum for 22 years, various works.

Note that the Wikipedia pages on these subjects are for once a poor source,
they suffer from speculation, superstition, tradition, "sainthood", and the
old school of form criticism ("Today it is no exaggeration to claim that a
whole spectrum of main assumptions underlying Bultmann's Synoptic Tradition
must be considered suspect." - Kelber, W.H.).

It is interesting that polemicists such as Richard Dawkins, Christopher
Hitchens tend to avoid confronting the historicity of Christ, and Christ
himself head on. They refuse to get into the ring, preferring easier prey. It
is ironic that the brother of Christopher Hitchens, Peter Hitchens, a renowned
journalist, would be an atheist who converted to Christ and has since written
on the subject of "the rage against God".

[1] - "Many have undertaken to draw up an account of the things that have been
fulfilled among us, just as they were handed down to us by those who from the
first were eyewitnesses and servants of the word. With this in mind, since I
myself have carefully investigated everything from the beginning, I too
decided to write an orderly account for you, most excellent Theophilus, so
that you may know the certainty of the things you have been taught." - Luke,
Luke 1

[2] - "I passed on to you what was most important and what had also been
passed on to me. Christ died for our sins, just as the Scriptures said. He was
buried, and he was raised from the dead on the third day, just as the
Scriptures said. He was seen by Peter and then by the Twelve. After that, he
was seen by more than 500 of his followers at one time, most of whom are still
alive, though some have died. Then he was seen by James and later by all the
apostles. Last of all, as though I had been born at the wrong time, I also saw
him. For I am the least of all the apostles. In fact, I'm not even worthy to
be called an apostle after the way I persecuted God's church." - Paul, 1
Corinthians 15:3-9

[3] - "And if Christ has not been raised, our preaching is useless and so is
your faith. More than that, we are then found to be false witnesses about God,
for we have testified about God that he raised Christ from the dead. […] But
Christ has indeed been raised from the dead, the first-fruits of those who
have fallen asleep." - Paul, 1 Corinthians 15:20

[4] - "That which was from the beginning, which we have heard, which we have
seen with our eyes, which we have looked at and our hands have touched — this
we proclaim concerning the Word [the Logos, light, reason] of life. The life
appeared; we have seen it and testify to it, and we proclaim to you the
eternal life, which was with the Father and has appeared to us. We proclaim to
you what we have seen and heard, so that you also may have fellowship with us.
And our fellowship is with the Father and with his Son, Jesus Christ. We write
this to make our joy complete." - John, 1 John 1

~~~
calebmpeterson
Though it is a small thing, I offer my deepest thanks for such a reply.

~~~
jorangreef
With pleasure, your comment showed great insight.

