Oh I see, sorry. I misunderstood the model. I thought it would be fine to measure a qubit, collect the outcome classically and then apply a correction on that same qubit (based on that classical outcome).
...(continued)I don't think this is unitary as written, you'd need to do measurements in the X basis (not just reset) and some classically controlled corrections depending on the measurement outcomes, right? E.g take f(x)=x, then this is just a teleportation protocol, and the corrections are obvious (conversely i
...(continued)Assuming one-way permutations exist, I think it should be in general hard to invert unitary-effect operations that involve measurements/feedback (this is similar to the examples you mentioned). Let f be a OWP. Then the mapping |x> -> |f(x)> is unitary, since it's just a permutation unitary. Given th
...(continued)Very interesting paper. Somewhat tangentially, in the introduction you mention
> Our standard rationale for being given access to both X and X† is as follows: we imagine that X is given as a quantum circuit on a scalable quantum computer, in which case X† can be performed by simply inverting the qu
...(continued)the 2D families in the paper referenced in the comment look to be exactly the same codes as the ones in the paper; the new angle seems to be constructing them as GB codes (with simple polynomials at that) which is pretty interesting. It would also be interesting to see if this can be extended to th
How does your result relate to the construction in https://arxiv.org/abs/2505.10403? They seem to share similar parameters.
Thanks for pointing this out! It is indeed helpful for us to see that this concept of global stationarity is important in other contexts, as our Lemma 3 derives global stationarity from the perspective of relational equilibrium (i.e. local subsystems being invariant).
...(continued)Coincidentally, the global stationarity given by Eq. (7) is also what I assumed to derive an unambiguous notion of time reversal for open quantum systems (in the context of time-reversal symmetry and detailed balance) in Proposition D.1 in https://arxiv.org/abs/2403.12896. Really cool to see it in w
...(continued)Interesting work! I'd like to shamelessly promote some earlier work of ours that studies the same problem of quantum metrology with environmental measurements, albeit using a larger-Hilbert-space approach:
Mankei Tsang, Howard M. Wiseman, and Carlton M. Caves, "Fundamental Quantum Limit to Wavefo
It seems that this now completely resolves our conjecture in https://arxiv.org/pdf/1608.05317, which already showed the "easy" direction of the bound.
...(continued)Yeah, I agree that with this setup the efficiency is likely too low.
That said... if you somehow have reliable storage, then efficiency stops being an issue for violating the inequality. The entanglement generation doesn't need to be spacelike separated, only the entanglement consumption. So you
...(continued)Sure, I'm no stranger to the usefulness of post-selection. As you point out, SPDC plus heralding is still the best way to get hold of single photons in quantum optics!
However, if you are going to use post-selection, you have to take into account the reduced efficiency. Otherwise, one would not
...(continued)I wouldn't be so hard on post-selection. It's very possible to analyze it in confusing ways, but I think it will ultimately be extremely useful for building larger systems.
For example, quantum networks will need to distribute entanglement across their links. The quality of that entanglement can be
...(continued)Just wanted to point out that (up to cyclic shifts) the polynomials for your [[12,2,3]] code are equivalent to (1+y) and (1+xy). These are the same polynomials used to generate the twisted torus in [Breuckmann and Eberhardt, 10.1109/TIT.2021.3097347, Figure 8] with the same code parameters. These 2
...(continued)I'm surprised to see so few comments. It is well-known that separable states cannot demonstrate any kind of non-locality, given the accepted definitions of these terms. See for instance the classic reviews on "Quantum Enganglement" by the Horodeckis (arxiv.org/abs/quant-ph/0702225) and "Bell nonloca
...(continued)I think a better title for this paper would be "producing entanglement by frustrated interference and mode measurements". The title's current claim that the state isn't entangled seems clearly disproven by equation 15 (the superposition before measurement). The state described in that equation is en
...(continued)Woke up to an email pointing out that a lot of this work overlaps with Appendix C of https://scirate.com/arxiv/2402.02185.
What is still unique to my paper?
- Showing this circuit increases the timelike distance
- Making the circuit remove leakageWill update the paper with a note credi
This very clear to me now. Thank you!
...(continued)Thank you for your question. In fusion-based quantum computation (FBQC), a quantum computation is executed by repeatedly generating copies of entangled few-qubit resource states and performing fusions (entangling two-qubit measurements) between pairs of resource states, as well as single-qubit measu
Figure 17 displays a `[[4, 2, 2]]` code where a `T` measurement is performed on the first qubit, a `Z` measurement on the second qubit, and `X` measurements on the third and fourth qubits.
How does the state injection work if all the states are collapsed at the beginning of the protocol?
It's been difficult verifying your results (figure 3). Do you have additional information that you can share on the circuit noise models you used for the two syndrome extraction methods?
> No other equations are affected.
Glad to know! Cheers :)
...(continued)Ah, you are correct! That equation should be equal to a sum over x and tilde x that are stabilizations, and not just permutations of one another. Many apologies, we expanded this section of the proof at a later stage for readability, and introduced this error.
This does not change any later steps
...(continued)Hi, and thanks for this very nice paper! I'm still reading it, but there's something I'm not sure to understand, and I hoped you could clarify it for me.
On page 22, below Equation (57), you write:
> When averaged, the global random phase $F$ enforces that $\tilde{x}$ and $x$ are related by a perm
I think some important references are missing, e.g., https://arxiv.org/abs/quant-ph/0401091 which shows a n^1.5 time algorithm for the single source shortest path problem up to polylog factors.
...(continued)Yes, the scenario you describe is possible. We cannot exclude it. The safest and most conservative statement is that "our work provides the framework for identifying the minimum instance sizes for quadvantage for this problem, given sota algos and machines".
If we are unlucky, this minimum is ver
...(continued)Hi, very nice review.
I particularly support the heuristics-minded approach to quantum advantage, as stated in this work: "Nevertheless, based on the comparative strength of classical optimization methods, we believe that the most promising path forward is to target individual problem classes and
Thanks for the comment. This is a neat observation! I agree with your conclusion.
...(continued)Hi, great paper! An optimization can be made to your construction in Section 2.2, which eliminates in Section 2.3 the dependence on the number of non-zero coefficients of $f$ (and consequently lets you take $n > 660$). The idea is as follows: $CX_{(n-1)\to Q_f}$ is originally written as
$$CX_{(n-
...(continued)We also struggled with a name and since the connectivity is in a strict sense not planar on a 2D lattice and also they are not really BB codes (the bicyclic referring a torus as the underlying lattice, or to them being two-block group algebra codes for the product of two cyclic groups) . I feel "til
...(continued)Hi!
I'm one of the authors of the paper.
I’d like to share that we plan to remove the third result regarding consistent-QPH in the next revision and replace it with a new insight.
For now, here are the key points raised by Dorian Rudolph:
$\mathsf{CQPH}$ can simulate $\mathsf{QPH}$ by si
Yes, I agree the paper is clear on the meaning of the term.
...(continued)Hi Craig, thank you for the comment.
We understand that in some contexts, particularly in graph theory, "planar" is taken to imply non-crossing edges, i.e., a planar graph. However, this is a specialized technical meaning. More generally, as supported by standard definitions, "planar" simply means
...(continued)(Not a serious issue, just some terminological confusion.)
I felt a bit tricked when I realized the "planar" in the title meant something different than I expected. I'd describe the property this paper is aiming for as "2d-local genus-0" or "planar boundaries". I think, in typical usage, "planar" m
The proof of Lemma 9 in this paper got messed up in the editing process for the v1 of this paper. A corrected proof is given below; it will appear in the arXiv v2 version. Thanks to Mingyu Sun for pointing out the error!
![Corrected proof][1]
[1]: http://www.cs.cmu.edu/~odonnell/proof.png
Great paper! Also, happy birthday to my amazing colleague Lennart — may your day be as insightful as this paper! 🎉
Is this related to https://en.wikipedia.org/wiki/Thomas_precession?
...(continued)As I wrote to the authors when they put out the initial version of this pre-print, and as explained in detail in [this repository][1], there is little point in analyzing the success probability of the last step of Shor's original classical post-processing as there are better ways to post-process the
...(continued)Thank you very much for your careful reading and constructive feedback.
We agree that the phrase "on planar architectures with only nearest-neighbor interactions" in the abstract may be misleading, as our study does not specify or analyze an explicit implementation using local gates. Our intentio
...(continued)I believe the result of section 7.1, regarding the maximal-magic qutrit states, is incomplete, and thus Conjecture 2 is false. [Fuchs and Cuffaro (2024)](https://scirate.com/arxiv/2412.21083) proved that maximal magic, as measured by the stabilizer Rényi entropy, obtains if and only if the state is
It was pointed out to me that there are similarities to https://arxiv.org/abs/quant-ph/9604028 which also works by trying to stay in the symmetric subspace, and was found to be flawed.
...(continued)This obviously doesn't work.
Essentially the proposed scheme is to run the noisy process N times, and recover results by averaging measurements. As the paper notes, this suppresses errors for a single qubit state undergoing a single round of noise. The problem is that this test completely misses th
It's not clear (to me) how you encode part of an entangled state with this code.
Do you expect anything qualitatively new emerges if one generalizes such a construction to 2D?
One of the very first papers to explore this question, produced when ChatGPT (v3.5) had just made its public debut, is this one: https://onlinelibrary.wiley.com/doi/epdf/10.1002/aaai.12113
...(continued)Thanks for your comments Jacques. We are discussing how to update the article in light of them.
I would prefer not to formulate Completeness in terms of "hidden variables". There were good reasons to rebrand hidden variable theories as "ontological models", and there are a lot of misconceptions
...(continued)Some of us QBists are discussing this article over email. We think that the way "Completeness" is elaborated in the article sits uncomfortably with QBism, possibly also with RQM.
The article frames the issue like this: either QM furnishes us with a "description" of the properties of physical syst
...(continued)Great paper! I've not had a chance to read it over in detail yet so forgive me if I've missed this but apart from a brief mention in the conclusion, you don't seem to have a discussion on the effects of resonator leakage on your gate fidelity. You state an advantage of your gate is that you can driv
Congratulations for this nice work!
We wanted to let you know of our earlier work in : https://arxiv.org/abs/2503.01738 where we consider an ensemble BP decoding method for the Bivariate Bicycle code family under circuit level noise, as well.
Braneshop, and
the US National Science Foundation.
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