iiinova — where your digital self keeps evolving

Reposted by Richard McCracken

Physghoul 👻 🎃 @physgal.bsky.social · 06/10/2026

My department is searching for two full-time continuing physics teaching faculty. Come work in beautiful BC. 🧪👩🏻‍🔬⚛️🎢🍎 @sfuscience.bsky.social

sfu.ca

Science

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Richard McCracken @rmccrackenhwu.bsky.social · 16/08/2026

I thought they were going to town on a cake

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Richard McCracken @rmccrackenhwu.bsky.social · 11/08/2026

I loved Children of Time and have just finished listening to Children of Ruin. I'm now ready to learn about space Corvids!

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Richard McCracken @rmccrackenhwu.bsky.social · 28/07/2026

*dad joke mode activated* You won’t die, but you might do yourself an injera

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HWU Physics @hwuphysics.bsky.social · 18/06/2026

Congratulations to the @heriotwattuni.bsky.social Physics graduating class of 2026! Our staff wish you all the best for the future, and please keep in touch!

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Binfire Era @binfire.bsky.social · 25/04/2026

Happy Miss Congeniality Day to all who celebrate!

Screenshots from Miss Congeniality. Subtitles read "Describe your perfect date.

That's a tough one. I'd have to say April 25th. Because it's not too hot and not too cold. All you need is a light jacket."

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Lum @brokentoys.social · 13/04/2026

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Eize Basa @eizebasa.baby · 05/04/2026

“I will NOT sacrifice the Oxford comma. We've made too many compromises already; too many retreats. They assimilate the em dash and we fall back. They capture ‘not just X but y’ and we fall back. Not again. The line must be drawn here! This far, no further!”

I know the tweet is Al generated when they use " ," before and.

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Richard McCracken @rmccrackenhwu.bsky.social · 31/03/2026

Presumably saying “everybody loves raiment”

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Numerical simulations give specific outcomes; SCEM gives the entire possibility space. Congratulations to Seb for this amazing work, and thank you to @derryckreid.bsky.social for providing some historical data for comparison. End 🧵

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Final test: compare SCEM (top) to numerical simulations (bottom). Result? Excellent agreement! 12/

Top, the combined SCEM result for our chosen crystal and pump, showing SPDC, SHG, SFG and DFG outputs simultaneously. Bottom, the output from a numerical simulation showing strong agreement.

Spiderman pointing at himself meme, captioned "analytical SCEM" and "numerical simulation"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

SCEM isn’t limited to SPDC. It generalizes naturally to SHG, SFG, higher-order QPM, and cascaded χ² processes, all combined on a common spectral basis. This is perfect for building full multi-stage interaction maps. 11/

"Voltron" toy combining together from different components. The components read "SHG", "SFG", "DGF", and "Cascaded Interactions", and combine to give "full SCEM framework"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Nice bonus: you only need to compute the crystal-only efficiency map once for a given material. Store it, and then reuse it with any pump spectrum or system design. That means rapid exploration without new QPM calculations every time. 10/

Man tapping his head with a caption saying "compute once, reuse forever"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Put it all together and we get the final SCEM. This reveals the true accessible gain regions for this pump–crystal combo. The key insight: gain is not uniform across the SPDC band. Some regions dominate; others are weak despite being phase matched. 9/

Final SCEM for this combo of pump and crystal. The gain is not uniformly distributed, but is concentrated in key wavelength bands.

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

When we combine the intrinsic efficiency, the extrinsic intensity scaling, and crystal length we get the full SCEM prefactor map. This is everything except the phase matching term, and it sets realistic limits on conversion potential. 8/

Power conversion efficiency scaled by pump spectrum

"Epic handshake meme". The left arm reads "Intrinsic conversion efficiency". The right arm reads "pump spectral weighting". The combined hands read "full SCEM predictor map"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Then insert the actual measured pump spectrum. The real pump filters the gain landscape dramatically, highlighting which phasematched regions are fed with power. 7/

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Now let’s add the intrinsic power-conversion efficiency. This shows which frequency pairs the crystal itself can efficiently convert, independent of the pump envelope - a major upgrade over pure sinc² models. 6/

"galaxy brain" meme. The small brain is captioned "using only sing-squared'. The normal brain is captioned "including prefactors". The galaxy brain is captioned "mapping the crystal power-conversion efficiency"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Next: switch to a broadband top-hat pump – now many pump wavelengths contribute simultaneously. The gain concentrates where QPM curves run steeply across the pump bandwidth – the first real “SCEM-like ” behaviour emerges. 5/

Phase-matching curves using a top-hat pump instead of monochromatic. The broadband nature of the phase matching space starts to emerge.

Happy and sad views on a bus meme. Sad view is captioned "Monochromatic pump". Happy view is captioned "Broadband top-hat pump".

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Let’s start simple, using a monochromatic pump and densely sampled grating periods. This reproduces conventional sinc² QPM curves, revealing a 2D gain map. 4/

An image of the phase matching across many grating periods

Spongebob "old faithful" meme, captioned "Nonlinear optics community" and "monochromatic pump since-squared curves"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

At the heart of SCEM is the parametric gain. This includes two crucial prefactors that are often ignored: the extrinsic: crystal length and spectral intensities of pump/idler, and the intrinsic: material-dependent power-conversion efficiency. 3/

An image of the parametric gain equation.

Charlie from "It's Always Sunny in Philadelphia" in front of his conspiracy board. Caption reads "It's more than just a sinc-squared term, I swear!"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

Standard sinc-squared QPM gain assumes a monochromatic pump & ignores frequency-dependent efficiency. But real ultrafast systems use broadband pulses with complex spectra! SCEM combines crystal properties and the real pump spectrum to map all possible conversion pathways in one picture. 2/

"Guy walking with his girlfriend getting distracted by a woman in a red dress" meme. The guy is tagged "nonlinear optics community"; the girlfriend is tagged "old sinc-squared monochromatic model"; the woman in the red dress is tagged "SCEM"

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Richard McCracken @rmccrackenhwu.bsky.social · 17/03/2026

PhD student Seb Robarts introduces Spectral-Crystal Efficiency Mapping (SCEM) – a new analytical tool for understanding broadband nonlinear conversion. 1/

Leonardo Dicaprio meme where he's pointing at the TV. The caption says "Me seeing a new nonlinear optics technique"

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Reposted by Richard McCracken

Ryan Nanni @celebrityhottub.bsky.social · 16/03/2026

"Open the Strait of Hormuz. You may not receive the help of any other sovereign nation. Fastest wins."

Fern Brady wearing a camera helmet on Taskmaster and opening the task, which has a red wax seal, and reading the contents. She has a purple set of coveralls on as well, which is just fun.

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Plashing Vole @plashingvole.bsky.social · 06/03/2026

This appalling fat cat wants to shut the door on all my mature students, many of whom left school after GCSE and give up a lot to go to university. I can tell him that they’re the hungriest for education and far from being unable to graduate, they regularly get the highest grades. Hateful man.

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Jordan aka Jirdan @slclunk.com · 28/02/2026

I think about this Tony Benn speech much more than I used to

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Aparna Nair @disabilitystor1.bsky.social · 23/02/2026

what even is the fucking point

How can Einstein do all this?
Einstein has his own virtual computer with a browser, just like you do. He can navigate websites, watch videos, read documents, type in text fields, click buttons, and submit forms. Anything you can do on a computer, Einstein can do.

How does Einstein access my Canvas?
You link your Canvas account once during setup. Einstein uses your credentials to log in, view assignments, and submit work on your behalf.

Will my professor know?
Einstein submits assignments from your account just like you would. The work is original and generated per-assignment — not copied from a database.

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Richard McCracken @rmccrackenhwu.bsky.social · 20/02/2026

Isn’t that what Abstracts are for?

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HWU Physics @hwuphysics.bsky.social · 28/01/2026

The application deadline of 30th January 2026 for the CDT in Applied Quantum Technologies is fast approaching. We have up to 18 fully-funded PhD places across our three themes of Quantum Measurement and Sensing, Quantum Computing and Simulation and Quantum Communications. Apply Now at aqt.ac.uk

aqt.ac.uk

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Prof Rachel Oliver @profrachelgan.bsky.social · 12/01/2026

Following coverage over the weekend of Sir Paul Nurse's comments that suggested that the only reason that a Fellow should be expelled from @royalsociety.org is scientific misconduct, I have written to him to explain the risks such an attitude poses of increasing sexual harassment in STEM.

Dear Sir Paul,

Re: Royal Society Code of Conduct

I am sure that many scientists have written to you about the specific question of Elon Musk’s Fellowship and whether, under the Royal Society’s Code of Conduct, his retaining that Fellowship is appropriate. I will not rehash these issues. Instead, as a female scientist with extensive experience of activities aiming to increase equality, diversity and inclusion in the engineering and physical sciences sector, I am writing to you (in a personal capacity) to ask you to reconsider the statements you have recently made in this context to the UK press about the Royal Society’s Code of Conduct and how it is applied.

A 2018 report from the joint National Academies of the United States of America, concluded that “sexual harassment is common in academic science, engineering, and medicine” and that “greater than 50 percent of women faculty and staff and 20–50 percent of women students encounter or experience sexually harassing conduct in academia”. This report described codes of conduct that make clear that sexual harassment is unethical and will not be tolerated as a “powerful incentive for change”. The authors also noted that sexual harassment can have significant and damaging effects on the integrity of research. In my own praxis, I have found that clear and consistently-implemented codes of conduct that address these issues make female scientists and engineers safer, and allow them to focus more effectively on their research. For codes of conduct to have such a positive effect, it is vital that sanctions for actions which transgress the code are meaningful and substantial.

I was hence aghast to realise that in an interview with the Financial Times published on 9/1/26, you appear to have suggested that the Royal Society “should only expel fellows if their science proved “faulty or fraudulent or highly defective””. Moreover, in a further interview with the Guardian on 11/1/26 you suggested that the code “may need to be looked at again”, with the implication that your aim would be to remove the option of sanctions on Fellows for reasons not strictly related to faults or defects in their research.

I suggest that changing the Royal Society’s code of conduct so that the likelihood of serious sanctions for sexual harassment is reduced, would directly endanger women who interact with the Royal Society at events or otherwise, and would provide a licence to harass to the already powerful people on whom the Society bestows fellowship. The implications of your words - that under your leadership the only infringements of the code which are likely to receive the sanction of the Fellowship being removed are those related to research misconduct - already risk empowering harassers. You stated, in the Financial Times interview, that “there’s many bad people around, but they have made scientific advances”. Given this awareness of the possibility of bad actors in our scientific community, it is wholly irresponsible to suggest that the Royal Society would not act to sanction these people if they harass more vulnerable scientists.

I am hence writing to request that you retract any suggestion that the Society’s Code of Conduct should be changed so that the only reason a Fellow might be sanctioned by the removal of their Fellowship is “faulty or fraudulent or highly defective” research. This action is necessary to safeguard female scientists, a requirement placed on the Society by safeguarding legislation and UK statutory guidance.

Yours sincerely,

Professor Rachel A. Oliver.

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Richard McCracken @rmccrackenhwu.bsky.social · 16/12/2025

Is it because you were going to say the word “taint”?

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Laura McInerney @missmc.bsky.social · 07/12/2025

My dad abhors any negative comments about immigrants. Asked him recently why he’s so strong on it: ‘Because we’re always happy to take the rich and clever ones. Which means it’s not about disliking immigrants. It’s about disliking the poor and vulnerable. And that’s a bad human instinct.’

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Richard McCracken @rmccrackenhwu.bsky.social · 07/11/2025

What’s the hidden gem in your catalogue? The work that didn’t take off as much as you might have hoped?

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Richard McCracken @rmccrackenhwu.bsky.social · 31/10/2025

Not sure if #icanhazPDF is still a thing, but does anyone have access to this conference paper doi.org/10.1117/12.2...?

doi.org

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Richard McCracken @rmccrackenhwu.bsky.social · 20/10/2025

Picasso was alive at the same time as Charles Darwin and Eminem

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Richard McCracken @rmccrackenhwu.bsky.social · 18/10/2025

@cwgabriel.bsky.social about to head on a field trip to South Africa if you or Kara want any long-distance gifts Others welcome also - 988414023273

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