Christopher K. Long

Christopher K. Long

@christopher-k-long.bsky.social

4th year PhD student at the University of Cambridge focusing on Quantum Computing (he/him) Google Scholar: https://scholar.google.com/citations?user=GRSIcsEAAAAJ GitHub: https://github.com/Christopher-K-Long ORCiD: https://orcid.org/0009-0001-3230-942X

262 Followers 361 Following 74 Posts Joined May 2025
1 month ago
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What’s purportedly wrong with Strunk & White’s “The Elements of Style”? I was reading the comments on this answer where several users claimed that Strunk and White’s The Elements of Style was “misinformed, hypocritical, and wrong” and “flat-out wrong or totally mislead...

[1] G. K. Pullum, 50 Years of Stupid Grammar Advice, The Chronicle of Higher Education, Apr. 2009. Original url:
www.chronicle.com/article/50-y.... PDF download from @archive.org (no sign-in required): web.archive.org/web/20260208....

[2] @archive.org: web.archive.org/web/20220811...

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1 month ago
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What’s purportedly wrong with Strunk & White’s “The Elements of Style”? I was reading the comments on this answer where several users claimed that Strunk and White’s The Elements of Style was “misinformed, hypocritical, and wrong” and “flat-out wrong or totally mislead...

I found Pullum's critical essay, 50 Years of Stupid Grammar Advice, helpful in discerning Strunk & White's rules from suggestions [1]. Pullum's essay is heavy-handed, and a counter-critique can be found in the following Stack Exchange answer: english.stackexchange.com/a/3223/695205 [2].

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1 month ago
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The Elements of Style, Fourth Edition ebook by William Strunk Jr - Rakuten Kobo Read "The Elements of Style, Fourth Edition" by William Strunk Jr available from Rakuten Kobo. 'The Elements of Style' (1918), by William Strunk, Jr., is an American English writing style guide. It is...

I finally read The Elements of Style by Strunk & White; I should have read it on day one of my PhD. At least I read it before writing my thesis. A free copy can be found on Kobo: www.kobo.com/ebook/the-el....

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1 month ago

I second the Hyperion Cantos

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1 month ago

I've only read a couple of books from the Hainish Cycle; now I'm really excited for the rest. Maybe the dispossessed will have to be next.

In the left hand of darkness at first names are used but not explained. After a few chapters some you can infer some and some are explained.

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2 months ago

Unfortunately, it looks like you need third-party apps to create markdown-style links on @bsky.app:

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2 months ago
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GitHub - Christopher-K-Long/GitLab-Repo-Sync: Tutorial for syncing GitHub repos to GitLab with a GitLab CI triggered by GitHub Webhook. Tutorial for syncing GitHub repos to GitLab with a GitLab CI triggered by GitHub Webhook. - Christopher-K-Long/GitLab-Repo-Sync

I have finally finished mirroring my scientific @github.com repositories to @gitlab.com. Here is a tutorial by [justncodes](github.com/justncodes) which I modified: github.com/Christopher-...

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2 months ago

Congrats on the successful year @mouhaqh.bsky.social, looks like I should your articles a read when I'm back to work!

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2 months ago
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2 months ago
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2 months ago

Now is not a good time for citations: Miss-citing online-only journals and Google Scholar indexing non-existent articles cited by hallucinating LLMs. Maybe the silver lining is that this will undermine metrics such as citation counts and h-indices, forcing academics to be judged more holistically.

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3 months ago

For example, numerical quantum optimal control techniques such as GRAPE and CRAB fall within the framework of VQAs and are used ubiquitously today to tune quantum processors.

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3 months ago

My point is I wouldn't declare VQAs doomed—that's too strong. Most no-go theorems have loopholes and assumptions. They tell us where it is still worth looking. I would just say that VQAs' use cases are increasingly constrained, and so there are probably more promising directions.

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3 months ago
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Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry - npj Quantum Information npj Quantum Information - Quantifying the effect of gate errors on variational quantum eigensolvers for quantum chemistry

Given the drastic improvements in noise tolerance of VQE algorithms since colleagues and I wrote [doi:10.1038/s41534-024-00808-x](doi.org/10.1038/s415...), it may even be possible to use coherently executed shots to improve the runtime of expectation value estimation.

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3 months ago

The large shot count is a problem. I hope that better techniques for estimating expectation values will be developed.

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3 months ago

Given that many alternative methods for eigenvalue estimation require polynomial overlap between the initial state and the eigenstate, it may be that VQAs are still needed for initial-state preparation.

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3 months ago

Guarantees are good but not vital. I think once there is good enough hardware someone will run the best known VQE for a molecule (like FeMoco) and it will either work or it won't. They will probably use tricks like adaptivity, pulse optimization, and error mitigation as asymptotics won't matter.

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3 months ago

Thank you for the reference, I will add it to the read list

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3 months ago
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Adaptive, problem-tailored variational quantum eigensolver mitigates rough parameter landscapes and barren plateaus - npj Quantum Information npj Quantum Information - Adaptive, problem-tailored variational quantum eigensolver mitigates rough parameter landscapes and barren plateaus

I agree with this for non-adaptive VQAs. Last I checked, no one had proved barren plateaus cause problems for adaptive VQAs—[numerical evidence](doi.org/10.1038/s415...) suggests the contrary. There is still some life in VQAs. Nonetheless, I'm glad to have diversified my research away from VQAs.

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4 months ago

Wish I could have gone, looking forward to #QuiDiQua4!

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4 months ago

Thank you for sharing this! Please give us an update of you hear back from Springer Nature.

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4 months ago
Keep Android Open Advocating for Android as a free, open platform for everyone to build apps on.

Starting next year, Android will no longer be the open computing platform we were promised: keepandroidopen.org

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4 months ago

At a glance this looks like it considers higher orders than Fermi's Golden rule so should give a better estimate. I hadn't thought about phonon spin coupling—which seems important in your use case. Phonon spin coupling could also be studied with Fermi's Golden rule. But higher orders are better.

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4 months ago

I think being hit by a meteroid might be harder to error correct than by a few cosmic rays...

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4 months ago

Let me know if this helps :)

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4 months ago

Note due to approximations the rule breaks down for large t. Differentiating this at t=0 will give the initial rate, R, where the approximations are most valid. The if amplitude damping noise is modeled as 1-e^{-t/T1} then differentiating at zero we can fit for T1 and we find T1=1/R.

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4 months ago

I don't know anything about diradical molecules, but hopeful the following is helpful:
In the stack I retain the sinc terms. You can either approx these as delta function first or just integrate the probability over the emission frequency. This will give total probability of emission after a time t.

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4 months ago
Taken from: https://en.wikipedia.org/wiki/Quantum_phase_estimation_algorithm#/media/File:PhaseCircuit.svg

Under CC BY-SA 4.0 License.
Author: Omrika
Created: 14 April 2023
Uploaded: 14 April 2023
Caption:
"The circuit of the quantum phase estimation algorithm, which estimates the phase of an eigenvector of a unitary matrix."

It looks like Bluesky doesn't like transparent images. Here is take two:

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4 months ago

"A good description of the phase estimation algorithm can be found in Mosca's Ph.D. thesis"—of which I found a copy here:
www.karlin.mff.cuni.cz/~holub/soubo...

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4 months ago
Quantum algorithms revisited | Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences Quantum computers use the quantum interference of different computational paths to enhance correct outcomes and suppress erroneous outcomes of computations. A common pattern underpinning quantum algor...

Cleve, Ekert, Macchiavello and Mosca (doi.org/10.1098/rspa...) "integrated several of the techniques of Shor and Kitaev"—section 5 and figure 6 present the algorithm as we know it today.

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