
“Qutrit” Experiments Are a First in Quantum Teleportation - gyre007
https://www.scientificamerican.com/article/qutrit-experiments-are-a-first-in-quantum-teleportation/
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sixdimensional
So, I guess this means that "qutrit" computing is kind of like ternary (or
"trinary") computing [1] with 3 well defined states. I got interested in
trinary when I read somewhere that Russian scientists had at one point built a
trinary computer (can't remember where I saw that) and I sat down and did the
trinary math because it was interesting - and it worked.

Perhaps in qubit computing (speculating as I am not an expert), it is harder
to detect the difference between the states which are somewhere in between 1
and 0, leading to the needs for error correction, but I also thought that,
that particular property of qubit computing was interesting for its
unpredictability, if it could be harnessed. Since a lot of machine learning
models (example, Monte Carlo) use randomness, I always wondered how lack of
precision might be an advantage. Out of my level of knowledge here a bit if
anyone has any thoughts.

I had to look it up and, I'm not a quantum expert, but it seems my gut feeling
was basically right: "Similar to the qubit, the qutrit is the unit of quantum
information that can be realized in suitable 3-level quantum systems. This is
analogous to the unit of classical information trit of ternary computers.
Note, however, that not all 3-level quantum systems are qutrits. The term "qu-
d-it" (quantum d-git) denotes the unit of quantum information that can be
realized in suitable d-level quantum systems." [2]

[1]
[https://en.wikipedia.org/wiki/Ternary_computer](https://en.wikipedia.org/wiki/Ternary_computer)

[2] [https://en.wikipedia.org/wiki/Qubit](https://en.wikipedia.org/wiki/Qubit)

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darsnack
You are right about qutrits. Essentially, anything that exhibits quantum
behavior is in infinitely many levels at once. It is our ability to measure
discrete levels that leads to qubits, qutrits, etc. Generally speaking, the
more levels the more unreliable the measurement.

As for Monte Carlo with respect to ML, are you referring to the “random walk”
aspect when you say “use randomness.” This refers to the fact that the method
samples one possible sequence of events and uses that sequence to update its
model. As opposed to dynamic programming methods where the value of all
possible sequences is estimated and used to update the model. Not sure that
the randomness from quantum is useful here. Where it could be useful is to
encourage exploration of the state space. So, normally Monte Carlo methods
have various tricks to make sure every sequence is sampled infinitely many
times. These tricks could be implemented by the error in quantum computing,
but I don’t know enough about the field to really be sure of that. And of
course it would help in that you could compute the results of many sequences
at once which is critical bottleneck in dynamic programming.

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sixdimensional
You're thinking in the same direction I am.. but I am definitely too far out
of my knowledge level to take it much further without sitting down and really
working hard on the problem. I'm going off the deep end here into what is
probably pop science or science fiction and might not make any sense at all. I
wish I understood more about this in detail.

I just always observed that quantum computing was interesting because certain
states seemed unpredictable, which is why scientists studying quantum
computing struggle when they don't get the expected states. If that
unpredictability is actually random due to the function of quantum states,
then it would provide a unique tool since true randomness really is not easily
found.

And the ability to potentially generate many random/expected states quickly -
yes, I was thinking about being able to generate/explore the space faster. Or
to use that in logical processing somehow as an advantage.

I have always been fascinated by a simple concept in logic - "maybe". I'm
borrowing from "fuzzy logic" a bit here and twisting it the way I wish for my
thought process. If one formalizes "yes","no" and "maybe" (i.e. 0, 1 and
something else), can one then make complex logical statements involving
probabilities, randomness, etc. by exploiting the "maybe" case.

For example, if I have one of those magic eight-balls, but it represents
quantum states - if I can clearly detect 1 or 0 but sometimes I get a 0.5 or a
0.8 unpredictably, how could I use that to my advantage...

Another line of thinking for this is neural networks, another thing which I
wonder could be accelerated by quantum computing. If I make the analogy that,
as a human with a brain that is like a neural network, when I am faced with
inputs that I have not processed before, my brain has to come up with a
solution to process it from my various experiences and it might product an
output that makes sense, or it might not.

Knowing my own fallibility here, if I know that sometimes I am faced with
inputs that I don't know how to process or didn't expect, I can find a logic
for how to handle those situations that might let me work around them.

[1]
[https://en.wikipedia.org/wiki/Fuzzy_logic](https://en.wikipedia.org/wiki/Fuzzy_logic)

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virattara
What I think, measurement of a qubit returns 0 or 1 always. The
unpredictability is in the part where you were expecting 0 and got 1 because
of noise I guess. But the measurement of a qubit in superposition does result
in a purely random result.

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smaili
For those thinking Star Trek, they literally address it a few paragraphs down
:)

 _The name quantum teleportation brings to mind a technology out of Star Trek,
where “transporters” can “beam” macroscale objects—even living humans—between
far-distant points in space. Reality is less glamorous. In quantum
teleportation, the states of two entangled particles are what is
transported—for instance, the spin of an electron. Even when far apart,
entangled particles share a mysterious connection; in the case of two
entangled electrons, whatever happens to one’s spin influences that of the
other, instantaneously._

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lossolo
Yes, this is interesting because it seems like information would travel faster
than light in this case, but based on our current knowledge about universe
this would break Einstein's Theory of Special Relativity, which could mean
there is some other _out of band_ channel of communication between entangled
particles.

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smogcutter
I've heard it analogized something like this: You and I have a deck of two
playing cards. We know which cards they are. We shuffle them, and each take
one without looking. Then we can travel as far from each other as we want, and
whenever I take a peek at my card I'll know _instantaneously_ what card you
have (and vice versa). We remain connected at a distance, but no information
really traveled faster than c and you and I couldn't use our knowledge of the
other's card to communicate.

~~~
perl4ever
Yeah, I've heard that analogy, and I've also read somewhere it's wrong,
despite sounding good. But unfortunately I didn't absorb the explanation of
why.

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jcims
One thing I always wonder with these quantum teleportation/communication
experiments is if they are actually dealing onesy twosy with photons or if
it's like a particle accelerator where they are dealing with millions/billions
and are just looking for the statistical outcomes and/or anomalies.

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abdullahkhalids
They deal with one photon at a time. The total number of events that are used
to estimate probabilities usually number in the hundreds or thousands, usually
collected over the course of hours or days.

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jcims
Awesome thanks!

