It's also available in the bar on the right of http://arxiv.org/abs/1609.06373
...(continued)The following paper found a setting in which adaptive operations do not help in quantum channel discrimination:
https://arxiv.org/abs/1408.3373
It is published as
Communications in Mathematical Physics, vol. 344, no. 3, pages 797-829, June 2016
http://link.springer.com/article/10.1007%2
Thank you for your kind words. Indeed, we worked hard to achieve the attributes you mentioned.
Spinning black holes are capable to implement complex quantum information processes with qubits encoded in the X-ray photons emitted by the accretion disk.
I do not find this second abstract more informative, and it is definitely less entertaining to read. I really like the original abstract because, despite its tale format, it really works as an informative abstract.
Sounds like a nice fable for young readers of [this book][1].
[1]: https://www.amazon.com/Quantum-Physics-Babies-Chris-Ferrie/dp/1492309532
...(continued)Here is the second (more informative) abstract:
We introduce a new quantum cryptographic primitive which we call
a tokenized signature scheme. Such a scheme can be used as an ordinary
digital signature scheme, with the additional property that the signer
can produce and distribute one-use quantum si
Many thanks for the clarification! I think I see your point (we had a similar issue with needing to have high overlap with input and output penalty in the universal adiabatic construction in my paper with Gosset and Vershynina, using the space-time construction).
...(continued)Thank you for the question! This construction due to Peres is interesting, but if I'm analyzing it correctly then I don't think it would work in the context of our paper. The ground state probability distribution of the Hamiltonian with couplings in Peres eq (20) looks like the ground state of a d
...(continued)In http://journals.aps.org/pra/abstract/10.1103/PhysRevA.32.3266 Asher Peres showed how to modify the Feynman Hamiltonian to make sure that a Hamiltonian evolution starting at t=0 lands after some fixed time at the desired output time so that the Hamiltonian effectively corresponds to that of large
The supplemental material is in the arXiv source. Once you extract the tarball, it's under anc/supplemental_material.pdf.
The supplemental material is missing! It would great to see the LP optimisation method used.
Is it actually decidable? :-)
I like this sentence from the conclusion: "There is, however, a second possible answer to our question: yes".
Here is a link for those who also haven't heard of SciPost before: https://scipost.org/
This is the very first paper of SciPost, waiting for the first paper of "Quantum" (http://quantum-journal.org). There are radical (and good!) changes going on in scientific publishing.
"Ni." would be slightly shorter, but some may find it offensive.
The abstract my be a bit too long.
I would suggest planets where life can really make a difference.
I am still trying to understand the following statement from II.A.
> This leads to the condition that the first- and second-order moments
> of the model and data distributions should be equal for the parameters
> to be optimal.
John also has an excellent series of 7 blog posts covering this material:
https://www.physicsforums.com/insights/struggles-continuum-part-1/
...(continued)I think that we have missed the "semi-" at the conclusion. Because, the proof of the theorem 4.3 is based on the using universal semi-density matrix concept which is not computable. The semi-computability concept used here is like the Kolmogorov complexity which is not computable and so the Cubic co
...(continued)I could well be missing something. But as far as I could tell from a rather quick read through the paper, all they show is that the quantum capacity of a channel with computable matrix elements is given by the regularised coherent information optimised over input ensembles with computable matrix ele
Do I understand correctly that this paper claims to show that quantum capacity is computable?
> After defining the algorithmic quantum capacity we have proved that it
> equals the standard one. Furthermore we have shown that it is
> computable.
That is really a long-term perspective.
Born in Italy, and now living in Scotland: I have no excuses not to feel inspired :-)
...(continued)It is not just in Scotland but in fact across the whole of UK and even beyond. I just found a reference, dating back to the very birth of quantum computing, where the early pioneers [already admit][1] that their work was inspired by Rabezzana Grignolino d'Asti.
[1]: https://scirate.com/arxiv/quan
A video of a talk I gave this morning will be [here][1], if it ever finishes uploading.
[1]: https://youtu.be/I8cMY0AmIY0
...(continued)Hi, sorry to just be updating this discussion now -- my conversation with Renato seemed to me to have converged here (and also continued via email and in person and I never updated scirate). However, a few people have asked what the outcome of our discussion was. So let me just say, that yes, my vie
Conjugate Gradient IS a Krylov-space method...
...(continued)I completely agree with your analysis, which describes the gedankenexperiment from a global (“outside”) perspective, according to the laws of Bohmian Mechanics (BM). And, indeed, it shows that the "memory" of a measurement outcome cannot assumed to be permanent, i.e., it may change (according to BM)
...(continued)Roger Colbeck drew our attention to this paper in the York QFIT group, and we met to discuss it last week. I would like to comment on the relation of Bohmian quantum mechanics to the extended Wigner's friend experiment. As generalised by John Bell, Bohmian qm can be applied to this experiment to yie
...(continued)Video of a *journal club* session about this paper, with a 20min explanation of the paradox and a long audience discussion about implications and interpretations:
http://pirsa.org/16060101/
Notation: "for simplicity" some names have been revealed (like the friends'), some have been changed
Too bad, the paper has been withdrawn due to a mistake :-/
...(continued)Maybe. But if your solution was not only self-consistent but also "single-world" then it would certainly contradict our theorem.
@Jonathan: I am unsure whether the concern you had is related to ($\star$), too, but I would anyway be interested to know whether it is this type of statements that you
If I had a self-consistent answer to that I'd be able to solve the measurement problem, no?
...(continued)OK, then we have identified the point where we disagree. Our assumption (QT) indeed corresponds to ($\star$), together with the understanding that the state is physically relevant.
Having said this, I am still curious to know how, in your opinion, experimenter F1 should derive her prediction ab
Yes, I would say so.
Could one then summarise your viewpoint as follows: Statement ($\star$) by itself is correct, but the state $\psi$ of the system is not the one that is physically relevant (i.e., we should not use it to deduce claims about the outcomes of future measurement on the system, for instance)?
...(continued)I think our point of disagreement is not $(\star)$ in itself, but rather the relevance of $\psi$ that enters this statement. I would also make the second bullet point stronger.
- When discussing erasure and subsequent measurements, one needs to keep track of both $E$ and $S$, even if they are no
...(continued)Yes, it may be easier to chat about this in person. But since I know a few who are following this discussion, let me at least summarise the points where I agree with you:
- In a scenario where experimenters are themselves subject to quantum measurements, it is not allowed to describe them using c
...(continued)The point I was originally trying to make was that the experimenter must be treated within the same framework as the system. The argument I was trying to make was that it is not always justified to treat the experimenter as classical (what I said above regarding the environment can be rephrased to t
...(continued)The example itself makes sense to me. However, I am unsure how it connects to the questions we were discussing.
Certainly, it illustrates that the statement ($\star$) mentioned earlier would be wrong if there was a non-trivial exchange Hamiltonian governing the interaction between experimenter a
...(continued)In a sense, yes, that's what I'm saying.
Let me take a situation that is very familiar to me: Cavity QED. We model a single-mode field inside a cavity with leaky mirrors by means of an interaction Hamiltonian like $\hat{H}_\text{int}=\mathrm{i}\hbar\int\mathrm{d}\omega\ \kappa(\omega)\bigl[\hat{b}(
...(continued)Just to make sure I got this correctly, are you saying that (at least in certain situations) the predictions we obtain when we use quantum theory depend on where we make the split between quantum system and measurement device? (This would raise the question whether there is a rule that tells us wher
...(continued)I won't attempt to solve the general problem. At least not without some beers.
My point was directed at the particular argument at hand.
- I have a laboratory $L$ inside which is a quantum system $S$ and an experimenter $E$
- $E$ performs some measurements on $S$, but $E$ is not treated as part
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