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John Travers

@jctravs.bsky.social
314 followers 273 following 27 posts

RAEng Chair in Emerging Technologies and Professor of Physics at Heriot Watt University, Edinburgh. Ultrafast optics, solitons, hollow fibres. lupo-lab.com

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Reposted by John Travers
Fabio Biancalana @fabiobiancalana.bsky.social · 25/06/2026
New arXiv preprint: I introduce the Quantum Split-Step Fourier (QSSF) algorithm for nonlinear waveguides. QSSF tracks input pulses together with quantum fluctuations, revealing that dispersive waves carry a low-dimensional Gaussian entanglement spectrum. arxiv.org/abs/2606.24643
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Carl T. Bergstrom @carlbergstrom.com · 27/01/2026
1. The thing about science that these jokers don't understand is that science cannot be vibe-coded. Whatever its flaws, the point with vibe coding is that you're trying to quickly make something that sorta works, where you can immediately sorta see if it sorta works and then sorta use it.
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C. Thi Nguyen @add-hawk.bsky.social · 22/01/2026
Last term I tried an experiment: I walked into my Tech and Design Ethics class, admitted that I had *no idea* what to do about ChatGPT - so I would let them figure it out. As in: their first project was to decide and write the ChatGPT policy for the class. Here's what happened:
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Peter Stockwell @stockwell.bsky.social · 19/12/2025
Physicist Leo Szilard, in a short science fiction story from 1948, describing how to retard science by making the funding application longer and harder than the proposed research - now called the ‘Szilard point’
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Prof Rachel Oliver @profrachelgan.bsky.social · 04/12/2025
This article suggests the possibility of training AI on pre-existing proposals and their review reports, scores and related decisions. I.e. training them on a system which is known to preferentially award larger amounts of money to white men. What could possibly go wrong?
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Jon Burke🌍 @jonburkeuk.bsky.social · 17/11/2025
Basic principles for the future of the car in cities: ✅ Fewer ✅ Smaller ✅ Slower ✅ Cleaner This can be achieved with: ✅ Parking controls ✅ LTNs ✅ Road User Pricing ✅ Pedestrianisation ✅ Default 20mph roads ✅ Improved public transport ✅ Segregated cycling
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Bohdan Pavuk @bpavuk.neocities.org · 26/12/2024
if you see this post, your actions are: - if you have a spare buck, give it to Wikipedia, then repost this - if you don't have a spare buck, just repost your action is mandatory for the world's best source of information to survive
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Katie Mack @astrokatie.com · 19/06/2025
Chatbots — LLMs — do not know facts and are not designed to be able to accurately answer factual questions. They are designed to find and mimic patterns of words, probabilistically. When they’re “right” it’s because correct things are often written down, so those patterns are frequent. That’s all.
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Shahid Kamal Ahmad @dancingmonkeys.net · 25/10/2025
Code is Just, all three seasons, as heavily requested, is finally out in a compiled PDF and ePub for easy reading. Price is whatever is reasonable for you, including zero. 1720541891659.gumroad.com/l/qkali
1720541891659.gumroad.com
Code is Just — The Compiled Edition
A record of the British home computer revolution — and my place in it. First told live on Twitter in 2021, now compiled, complete, and yours to keep.Code is Just began as a live Twitter thread in 2021...
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Seth Axen 🪓 @sethaxen.com · 03/10/2025
"Matlab is the Visual Basic 6 of technical computing." #HeardAtJuliaCon #JuliaCon #JuliaLang
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John Dudley @johnmdudley.bsky.social · 09/09/2025
If you love supercontinuum (and who doesn't!) check out our forward-looking Perspective in EPL which is free to read. Thanks @jctravs.bsky.social Thibaut Sylvestre, Alex Heidt, Roy Taylor, Goery Genty iopscience.iop.org/article/10.1...
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Richard Stupart @richardstupart.com · 31/07/2025
If you are applying to a PhD, don't use an LLM in composing your proposal. If you are doing a PhD, don't use an LLM to do the writing and reading and thinking for you. Sorry, I am going to die on this hill.
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John Travers @jctravs.bsky.social · 23/06/2025
Visit my group's post-deadline talk at CLEO/Europe-EQEC to find out what's been consuming an enormous amount of our time, energy and money(!) lately. Nikoleta Kotsina will present TW-scale optical attosecond pulses and sub-3 fs DUV pulses with more than 170 µJ of energy!! 🧪💡⚛️😎
Post-deadline PD-2.3 18:05 ICM - Room 13b

Extreme Soliton Dynamics for Terawatt-Scale Optical Attosecond Pulses and 30 GW-Scale Sub-3 fs Far-ultraviolet Pulses

Nikoleta Kotsina, Michael Heynck, Joleik Nordmann, Martin Gebhardt, Teodora Grigorova, Christian Brahms, and John C. Travers
Heriot-Watt University, Edinburgh, United Kingdom

We present the extreme soliton (XSOL) beamline, which generates terawatt-scale sub-femtosecond self-compressed visible-infrared pulses as well as sub-3 fs far-ultraviolet pulses with energy exceeding 170 µJ at 240 nm and wavelength tunability down to 140 nm.
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John Travers @jctravs.bsky.social · 14/06/2025
Congratulations to @nickkarpowicz.bsky.social and co-authors! This is a major contribution to our field. I am still digesting the details, but this is a wonderful piece of work!
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Kerrianne Harrington @kharrington.bsky.social · 13/06/2025
🎉New paper! doi.org/10.1364/OE.5... 📝 We look at how different numbers of capillaries affect the guidance properties of hollow core fibres, enabling the guidance of ~ 50 modes in the near-infrared. Some cool fibres in here that guide the visible and ultraviolet #science #optics #photonics
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Katie Mack @astrokatie.com · 03/06/2025
If you burn down a forest, you don't miss out on lumber for just that season. You have to replant all the trees, nurture them, and wait for them to grow. The science and research budget cuts happening now are wanton, senseless arson. Recovery, if it ever happens, will take generations.
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Kevin Dean @kevin-dean.bsky.social · 25/05/2025
Why are my lasers so expensive?
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Leah Murphy @leahrmurphy.bsky.social · 22/05/2025
Our optica paper, "Tunable megawatt-scale sub-20 fs visible pulses from a fiber laser source", is out! Happy to have been a part of this during my time at Heriot-Watt opg.optica.org/optica/fullt...
opg.optica.org
Optica Publishing Group
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John Dudley @johnmdudley.bsky.social · 21/04/2025
Announcing a PhD position starting October 2025, on Applications of Machine Learning in Ultrafast Nonlinear Fibre Optics. The advertisement will be out soon, but my email is easy to find, so please send me a CV if interested. Experience in experimental & numerical photonics highly desirable!
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Sam Halpert @samhalpert.bsky.social · 15/04/2025
Even accepting the premise that AI produces useful writing (which no one should), using AI in education is like using a forklift at the gym. The weights do not actually need to be moved from place to place. That is not the work. The work is what happens within you.
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Kerrianne Harrington @kharrington.bsky.social · 26/02/2025
The @uniofbath.bsky.social Optical Fibres group is hiring! They are looking for a Professor and two Lecturers to join. If bespoke optical fibres could benefit your research, this is an opportunity. More info: www.bath.ac.uk/research-gro...
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Paul Fairie @paulisci.bsky.social · 21/02/2025
A Brief History of Kids Today Have Too Much Freedom 🧵
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Kerrianne Harrington @kharrington.bsky.social · 23/01/2025
Traditional multi-mode #optical fibres are straightforward, but the same is difficult to achieve in hollow core fibres. We report anti-resonant hollow core optical fibres guiding at least 50 spatial modes in the infrared (~5-fold improvement ). #science #photonics #research arxiv.org/abs/2501.12996
Three hollow core fibres rendered in blender. They have a higher number of cladding elements, so offer more multi-mode capacity.
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Charlotte Garden @charlottegarden.bsky.social · 22/01/2025
An embarrassment of riches
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Dr. Stefan Haessler @stefanhaessler.de · 08/01/2025
Our recent paper in @opticapubsgroup.bsky.social Optics Letters presents the first relativistic plasma-mirror high harmonic generation on a liquid-sheet target. This is a real game changer for plasma mirrors ! Persistent kHz-rep.-rate with unprecedented stability. doi.org/10.1364/OL.5...
doi.org
Continuous relativistic high-harmonic generation from a kHz liquid-sheet plasma mirror
We report on continuous high-harmonic generation (HHG) at 1 kHz repetition rate from a liquid-sheet plasma mirror driven by relativistic-intensity near-single-cycle light transients. Through precise c...
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John Dudley @johnmdudley.bsky.social · 08/01/2025
A warm and wonderful recognition of Wilson Sibbett written by friend and colleague Roy Taylor in the latest issue of Nature Photonics. I am unsure about access options so (lower resolution) screenshots are below. www.nature.com/articles/s41...
Obituary of Wilson Sibbett - Page 1 Obituary of Wilson Sibbett - Page 2
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HWU Physics @hwuphysics.bsky.social · 07/01/2025
We are pleased to announce the launch of our new MSc in Quantum Technologies at Heriot-Watt University's Edinburgh campus. www.hw.ac.uk/study/postgr...
hw.ac.uk
MSc Quantum Technologies
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John Travers @jctravs.bsky.social · 17/12/2024
I'm hiring! Please share! I'm seeking a talented and motivated scientist to lead a research programme developing ultrafast light-source technologies in collaboration with a major player in the semiconductor lithography sector. Come and join my group at Heriot-Watt University, Edinburgh, Scotland!
enzj.fa.em3.oraclecloud.com
Postdoctoral Research Associate in Ultrafast Nonlinear Optics in Gas-Filled Fibres
The project is expected to lead to significant technological progress and high-impact scientific publications in the areas of ultrafast and nonlinear optics.
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Richard McCracken @rmccrackenhwu.bsky.social · 23/12/2024
Make sure you use an ultrashort pulsed potato masher when preparing your Christmas dinner #physics #nonlinearoptics
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John Travers @jctravs.bsky.social · 18/12/2024
I have two 3.5 year PhD positions available in my group (worldwide eligibility). Please share! I'm seeking motivated and capable PhD candidates who wish to work on state-of-the-art ultrafast light source science and technology. www.findaphd.com/phds/project... www.findaphd.com/phds/project...
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John Travers @jctravs.bsky.social · 17/12/2024
I'm hiring! Please share! I'm seeking a talented and motivated scientist to lead a research programme developing ultrafast light-source technologies in collaboration with a major player in the semiconductor lithography sector. Come and join my group at Heriot-Watt University, Edinburgh, Scotland!
enzj.fa.em3.oraclecloud.com
Postdoctoral Research Associate in Ultrafast Nonlinear Optics in Gas-Filled Fibres
The project is expected to lead to significant technological progress and high-impact scientific publications in the areas of ultrafast and nonlinear optics.
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Richard Herring @herring1967.bsky.social · 15/12/2024
www.theguardian.com/education/20... Can’t wait to tell the reverend that God isn’t real and that when you’re dead there’s nothing. Hope it makes him cry.
theguardian.com
Ho-ho-no! Children in tears after vicar tells them Santa is not real
Rev Dr Paul Chamberlain apologises for talk at Hampshire school after angry parents say he ‘ruined Christmas’
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Kerrianne Harrington @kharrington.bsky.social · 12/12/2024
Presenting 'u-Care #wrapped' for our last '24 meeting! 🎁🎶 Hope they're Spotify fans 😂 🟣 #UV #opticalfibre to 190 nm doi.org/10.1364/OE.5... 🔅 #deep-UV gen. in a hollow core fibre (HCF) doi.org/10.1364/OL.5... 🟢 UVA absorption in HCF doi.org/10.1364/OE.5... 🔬Multi-core HCF doi.org/10.1364/OL.5...
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David Ho @davidho.bsky.social · 24/11/2024
A person on a bicycle is by far the most energy-efficient among animals and machines per distance traveled relative to body weight. The bicycle is magic. www.jstor.org/stable/24923...
A graph titled "Cost of Transport" showing the relationship between body weight (in kilograms) and energy consumption for distance traveled (calories per gram per kilometer) for various animals and machines. It highlights that a person on a bicycle ranks first in efficiency.
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Seamus Blackley @seamus.bsky.social · 03/12/2024
The trick, my friends, is to go on living your life, full of love and passion, as powerfully as you are able.
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Jacopo Bertolotti @jacopobertolotti.com · 02/12/2024
Scientist types as #DnD classes: Fighter: The best way to approach any problem is to do an experiment first and ask questions later (assuming there is any question left to ask). Very high volume of fire, but needs a constant stream of money to pay for fancier and fancier equipment. 1/
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Julia Language @julialang.org · 25/11/2024
Hello @bsky.app from the #JuliaLang community! We're excited to start posting here on Bluesky in addition to our other social media, all of which can be found here: julialang.org We'll keep you updated on our fantastic community, our conferences, #JuliaLang updates, and more on this profile!
Julia REPL which activates the Bluesky project, and calls a function which simulates creating a new post on the julialanguage Bluesky account!
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Niko @nikosarcevic.com · 24/11/2024
Bonnie Scotland 🏴󠁧󠁢󠁳󠁣󠁴󠁿
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Kerrianne Harrington @kharrington.bsky.social · 21/11/2024
Hi all! Lots of new activity here, so I will introduce myself! I'm a UK early career researcher in photonics. I 🔹 Fabricate novel optical fibres 🔹 Post-process them to create advanced devices 💡 Focused on UV hollow-core fibres & applications in healthcare. I use bsky to post about my research 🔬
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John Travers @jctravs.bsky.social · 20/11/2024
My fist computer was the ZX Spectrum. Great memories - I can steel feel the soft rubbery keys!
An issue 2 1982 ZX Spectrum
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Ed Conway @edconway.bsky.social · 19/11/2024
🧵SALT🧵 It's been snowing in the UK and the road gritters are out in force, begging the question: Have you ever wondered where that grit actually COMES from? The answer is more magical, beautiful and fascinating than you probably realised. 1/14
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Seamus Blackley @seamus.bsky.social · 17/11/2024
Reader, I do not know the demons that haunt your dreams, the frustrations and insults of life that have brought you to your knees, the sadness you battle in your heart. But know this: there is pure goodness in this world. It exists. Sometime we see a glimpse of it. Today, I got such a peek.
The lucky author holds a single, roasted cacao bean with 1/2 the shell removed so we can see the pure chocolate inside. Behind his hand is a roasting tray filled with beans. 

The smell. THE SMELL. This photo shows an aluminum roasting tray filled with a layer of cacao beans. When roasting, the aroma of the fermentation suddenly gives way to the overwhelming joy of fresh brownies. Yes, there is a spirit watching over us all.
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Shahid Kamal Ahmad @dancingmonkeys.net · 12/11/2024
I’m going to post “Code is Just” here the same way as I did originally on Twitter, one day at a time, starting tomorrow. If you read and loved the original, as I know so many of you did, I’d feel grateful if you’d talk about it in your own words, though don’t feel obliged of course. 🧵👇🏽tomorrow
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John Travers @jctravs.bsky.social · 11/11/2024
I’m really looking forward to the attosecond physics session this morning at the IEEE Photonics Conference (IPC) in Rome. 💡
Listing of session talks
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