Earl Campbell

38 points to my daughter!

Congrats on a great word.

YouTube video by Marie-Celestine I sing with my father - Take Me Back To Eden @Sleep-Token wait for the low note #fatherdaughter

So deep, it took me a while to realise it was human:

youtube.com/watch?v=DRwJ...

I was expecting "expert prediction" to be a third-party authority, and found that framing to be weird.

I remember seeing project outlines in 2005-2008 saying things like, we will have a fault-tolerant million qubit device in 3 years. If anything, roadmaps have gotten better (more accurate/realistic) since then.

Quantum Computing Roadmaps: A Look at The Maps And Predictions of Major Quantum Players As of early 2025, major players are shaping the future with detailed roadmaps and predictions from their expert.

Roadmaps! Useful guides for the wider community, or overly simplistic and prone to exaggeration (sometimes, but not always!) ?

thequantuminsider.com/2025/05/16/q...

I ask because we are reviewing our roadmap:
www.riverlane.com/press-releas...

What would you like to know, or do you ignore these?

Mama etna has calmed down in time for our flight home to be undisturbed.

Surreal to see videos of scary fast pyroclastic flows only a few days after we had a tour up there! (Check the news if you don’t know what I am talking about)

Family holiday. At a loss to name this mythical creature, maybe it is the long forgotten mercentaur! It looks functional for neither sea nor land.

His star role in “the divincenzo code” including incredible evil scientist dance moves

youtube.com/clip/Ugkxaxa...

Professor Ian Walmsley to lead Oxford Quantum Institute Professor Ian Walmsley CBE FRS has been appointed Director of the Oxford Quantum Institute at Oxford University.

Quantum news: Prof Walmsley returns to Oxford to lead Oxford Quantum Institute

www.physics.ox.ac.uk/news/profess...

Well deserved, alas the bio in the article misses out one of his most notable career moments, ….

Quantum Algorithms Researcher - Riverlane Cambridge, UK | Full-time or Part-time | Permanent | HybridSalary: £55,000 to £80,000 DOEThe salary range for this role is broad as we are able to consider varying levels of experience.  Any offe...

We have an open rolling advert for QEC researchers at Riverlane. And now also have a single post to fill for an (error-corrected) algorithms researcher

apply.workable.com/riverlane/j/...

I'm often asked if I'll redo the 2019 quantum factoring estimate. Denser storage by yokes, smaller magic factories by cultivation, slimmer approx arithmetic by Chevignard et al… surely the cost is lower now?

Yes, it's lower now.

security.googleblog.com/2025/05/trac...

arxiv.org/abs/2505.15917

Google quantum symposium is fantastic. But many of the results presented are not on the arXiv yet, and we’ve been asked to not post about them on social media. So, sorry, no live update folks. But I can say cool stuff is coming!

When your marketing celebs get old and need name tags to be recognisable. LA highlights.

Death by surface code!

Nice catalog of talks here.

Jet lagged and adjusting

I highly recommend this paper.

[EPIC POST-PLANE POST FINISHED]

There are also a bunch of other tricks in there like optimization of electron orbital basis to minimize a crucial parameter Lambda, also clearly a smart thing to do. Of course, the devil is in the details, and the work is brilliantly executed.

What is the main contribution of Gunther et al?  They explore the more LCU based approach (leaving behind diamond norms) while also using a “best of both worlds” approach.   This is clearly the right thing to do and was a combination that I never got to exploring.

Gunther does a fantastic job of reviewing these connections and is a far better intro to the subject than any other that I have read so far.

So it was lovely to read Gunther et al and return to the topic.  Firstly, there are a bunch of connections, especially between my papers 1 and 3 above, which have never been very well explained the literature.

And over the years, I have been excited to see lots of papers and conference posters on randomized approaches, from people including Eisert, Weibe, Guzik, and others.  I read some of these, but many are still in que (for another plane journey!) and I am sure I missed some gems.

After [1,2,3] I disconnected from this research area a bit. Despite having a list of ideas on what to do next, I switched over to being more focused on QEC.

And after a tour de force of Mathematics from Kianna, we had want I considered a very beautiful result with improved resource estimates. Though the resource estimates were still not competitive except under some extreme assumptions discussed there.

3 - Later, while at AWS with Kianna Wan and Mario Berta, we realized that for phase estimation problem we only need an LCU decomposition of some target unitary.

But crucially, we were still stuck in terms of diamond norm analysis, and getting away from this mindset would prove to be crucial to really cracking the problem.

2 - It was clear even then to me, that qdrift was suboptimal and that some kind of hybrid deterministic and randomized method would allow a “best of both” approach. At Sheffield, with Yingkai and David, we made some progress with the SparSto protocol.

Errors were measured with respect to the diamond norm.  In the appendices, I attempted a resource analysis of phase estimation, but I was lacking the tools / knowledge of the literature, and It wasn’t great!

This showed that quantum simulation (and phase estimation) were possible with a gate count independent of the number of terms in the Hamiltonian, but with worse scaling w.r.t other parameters.

 1 - I came up with the qdrift algorithm I fondly remember working on it in the evening after my young kids had gone to bed, keen to finish the work as I knew it was special.