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29 February (2024)
26 February (2024)
Replying to @Elysee
La médiocrité la plus crasse en mal de sensations fortes.
Replying to @LCI
On peut désormais s'attendre à une frappe tactique préventive, de n'importe quel côté, d'ailleurs, et ciblant n'importe quoi, ça n'a pas grande importance.
24 February (2024)
Replying to @MyLordBebo
She might be correct, except that the fault lies with those who violated international legality before Russia did: laussy.org/wiki/Blog:Fabr…
23 February (2024)
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 2: the paper.
Part 1 here:
Part 2: the paper.
Part 1 here:
Fabrice Laussy @fplaussy · 22 Feb 2024
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 1: Kindergarten.
Niels Bohr founded 𝑄𝑢𝑎𝑛𝑡𝑢𝑚 Mechanics by 𝑄𝑢𝑎𝑛𝑡𝑖𝑧𝑖𝑛𝑔 angular momentum of the electron going round the nucleus. He became to Rydberg's empirical spectral lines what Newton was to Kepler's orbits.
Part 1: Kindergarten.
Niels Bohr founded 𝑄𝑢𝑎𝑛𝑡𝑢𝑚 Mechanics by 𝑄𝑢𝑎𝑛𝑡𝑖𝑧𝑖𝑛𝑔 angular momentum of the electron going round the nucleus. He became to Rydberg's empirical spectral lines what Newton was to Kepler's orbits.
arxiv.org/abs/2402.14010
Here are all the details about our mysterious circle.
Here are all the details about our mysterious circle.
Elena was the 1st generation of the Newton Fellowship from the @royalsociety, in 2009. Here you see her in Woolsthorpe manor with what I think is the best rendition of Isaac, by Thornhill (much more genuine-looking than the better-known portrait by Kneller)
This was an outstanding Fellowship when it started, with exceptional and insightful conditions, such as ten years of funding *after* the Fellowship ended, to provide conditions of long-term financial independence. Of course this was abandonned in mid-flight.
2009+15=2024 and the Roy Soc invited its fellows to a 15th-anniversary text for their venerable Philosophical Transations, the oldest Scientific Journal, giving some accompt of the present undertakings, studies and labours of the ingenious in many considerable parts of the world.
We had the perfect text for that journal, that hosted some of the most important works of mankind, including Maxwell's dynamical theory of the electromagnetic field. If some scientific literature tastes like honey, this is it:
Our contribution is the science we've been working on since about 2009 indeed, with one breakthrough the theory of frequency-resolved multiphoton correlations, published in 2012 journals.aps.org/prl/abstract/1…
And more recently, our theory of multiphoton quantum interferences, which we struggled to publish as this was covering too much in one go. We eventually had the bulk of it in Laser & Phot. Rev. onlinelibrary.wiley.com/doi/10.1002/lp… after a long editorial journey laussy.org/wiki/Blog:Scie…
Now although these two pillars of our work—both impulsed by Elena—were supporting independent lines of research, something very beautiful happens: they meet, to produce something that had been haunting me for years: the circle of antibunching.
I stopped counting all the stupid ideas I had to explain this circle, from caustics to antibundles passing by artifacts. Out of some unrelated problem, that I will introduce in part 3 of this twitter pullover (series of threads), Eduardo & Elena one day came up with the solution.
A meeting point of ideas is always a big Aha moment. If you can't wait to know, you can read the paper: everything is in there. But since it synthetizes much of what Elena and I have been doing these last 15 years (besides our two little girls) it's a lot to take in in one shot.
I suspect we're really writing for the AI nowadays; we're training these little bitches with one thing or two about photons before they take over. It's definitely too much for the average referee, complaining about "philosophical" aspects of our work! So Phil Trans here we come!
Next part I'll try to provide a self-contained description—which is also what the paper aims to do—but in 20 tweets as opposed to 22 pages (+7 of references), for the benefits of the 5 sophisticated conspiracy physicists (not all are theorists) who are reading this.
Part 3 here:
Fabrice Laussy @fplaussy · 11 Mar 2024
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 3: the circle.
Part 1 here:
Hello again, conspiracy physicists...
Part 3: the circle.
Part 1 here:
Hello again, conspiracy physicists...
Replying to @polyquantique
thanks, didn't know this work, looks extremely related, will dive into it immediately!
22 February (2024)
I want to go there! Douglas Adams was explaining one's fear of heights as an ancestral root with birds triggering a primeval urge to jump, paralyzed by a maddening fear not to. Close to a spiritual experience! I put this on my list of places to go (Zhangjiajie Glass Bridge).
The demonstrations of conservation of momentum are starting to go too far. But there's no other way to interest young people nowadays.
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 1: Kindergarten.
Niels Bohr founded 𝑄𝑢𝑎𝑛𝑡𝑢𝑚 Mechanics by 𝑄𝑢𝑎𝑛𝑡𝑖𝑧𝑖𝑛𝑔 angular momentum of the electron going round the nucleus. He became to Rydberg's empirical spectral lines what Newton was to Kepler's orbits.
Part 1: Kindergarten.
Niels Bohr founded 𝑄𝑢𝑎𝑛𝑡𝑢𝑚 Mechanics by 𝑄𝑢𝑎𝑛𝑡𝑖𝑧𝑖𝑛𝑔 angular momentum of the electron going round the nucleus. He became to Rydberg's empirical spectral lines what Newton was to Kepler's orbits.
Quantum theory quickly became wild, with Schrödinger (who was sorry he ever had anything to do with it)'s equation providing a shell structure (n,l,m) for Bohr's orbitals, making some transitions, like 2s→1s, forbidden!
Comes Goeppert Mayer, miss Nobel Prize, who goes 2nd order in perturbation theory and proposes a "𝐷𝑜𝑝𝑝𝑒𝑙𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛" or two-photon emission, connecting two first-order forbidden-transition states.
(She didn't do that for Hydrogen—Breit and Teller did—and apparently she didn't make the first use of second-order process for this type of transitions either—Podolsky (the suspected QUANTUM spy working for the Russians) better known as the P between E & R—did it the year before)
This process is important for a conundrum in astronomy: why do planetary nebulae feature a continuum spectrum, as shown bottom left for Orion? This the 2s→1s two-photon emission. If you break a Lyman photon in two, it becomes visible. Space has enough of those to be measurable.
But back to Earth, let me introduce the legendary Benjamin Mollow, who, on page 1969 of Christmas 1969's edition of The Physical Review, computes the spectral shape of resonance fluorescence, now known as the Mollow triplet. You can play with it here: demonstrations.wolfram.com/MollowTriplet
I have no end of fascination for both Mollow himself and his triplet. Like when Bobby Fischer was shown a game of Chess and wanted to do only that for the rest of his life, when I saw the mechanism behind the Mollow triplet I wanted to study only that for the rest of my PhD.
We've been studying it together with Elena for the past 20 years. This shows one of the big ideas—from Reynaud and Cohen-Tannoudji—where the triplet is explained as Bohr transitions between dressed states (shown in our dissipative Jaynes-Cumming ladder journals.aps.org/pra/abstract/1…)
Here there is something obvious to do, which however seems to have escaped notice. How about bringing Goeppert Mayer in the ladder? Because in our case that jumps over an intermediate stair, we called this process a leapfrog transition. The two photons also form a continuum.
Why did this escape notice? 1) Because people didn't think there was anything to see: when you look at the Mollow triplet, you see three lines, you wouldn't think to look for something which isn't there anyway. For the nebulae, there was a *visible* continuous spectrum, remember.
This is a tragic oversight because there is 𝑠𝑜 𝑚𝑢𝑐ℎ to see; but 2) you need the proper tools and 3) a conceptual leap. The tool is our theory of frequency-resolved photon correlations:
journals.aps.org/prl/abstract/1…
journals.aps.org/prl/abstract/1…
The conceptual leap is that physics at the two-photon level is a turf of its own, where single-photon hoodlums don't own the streets, have no say, aren't welcomed, not relevant, not needed, basta, get out, when you go two-photon, you enter a new realm, an independent dimension...
That's why people didn't see those leapfrogs. They didn't think they could be there if not visible one way or the other through one-photon observables. And even if they had conceptualized it, they couldn't have computed them because that's the sort of things they had to deal with
That is a nasty integral. It was painful even to grab a snapshot of it. Its courageous Authors [PRA 45:8045, 1992] comment about it:
What they demonstrate in the next section, however, is how to throw the baby out with the bathwater. They make approximations based on the one-photon picture: the spectral peaks. The two-photon baby, however, bathes away from the peaks, which are in the one-photon waters.
Our Theory of Frequency-Filtered and Time-Resolved N-Photon Correlations [PRL 109:183601 2012] is a game-changer. It allows to compute all this stuff i) easily, ii) exactly (with no approximation) and iii) always. The trick is insightful but I will jump straight to the results.
A first paradigm change is that one needs two axes to look at two photons. And you're not looking at intensity—this is a single-photon concept—but at correlations. Besides their magnitude, their type is important, which we encode with a color: 🟦(⬜) [🟥] is - (0) [+] correlated.
So now let's put our two-photon goggles and look at the Mollow triplet. Wow! They don't teach you this in textbooks, do they? Except those I write myself. What we see down here is a two-photon Mollow triplet. It is continuous, like the nebulae. I'm sure you understand it already.
Importantly: this is always there to see. As long as you look at photon correlations. The structure vanishes if you remove the glasses. This I'm less sure many people will understand. Nevermind, all this is old stuff anyway, over a decade old now: iopscience.iop.org/article/10.108…
What is new is that if you detune your laser off your atom, the one-photon spectrum remains about the same, in particular it stays symmetric. But the two-photon spectrum transmutes into something completely different, with an eerie circle cast into a sort of pyramid!
Well, not even that is new, we had observed it back in at least 2012, November 23, 20:57:27, arXiv tells me. What is really new (at last!) is that now we understand it. We know what it is. Here's the formula for the whole thing:
So we're not even started. It'll take us a few more chapters like this to get to the bottom. We can do it the hard way, which is the paper (part 2), the fun way (part 3) or the fast way (part 4). Or you can ignore it. But it's there and it's coming for you
Fabrice Laussy @fplaussy · 18 Apr 2023
Why there is a circle of antibunching in two-photon spectra...
Part 2:
Part 3:
Part 4:
Part 3:
Part 4:
Fabrice Laussy @fplaussy · 23 Feb 2024
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 2: the paper.
Part 1 here:
Part 2: the paper.
Part 1 here:
Fabrice Laussy @fplaussy · 11 Mar 2024
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 3: the circle.
Part 1 here:
Hello again, conspiracy physicists...
Part 3: the circle.
Part 1 here:
Hello again, conspiracy physicists...
Fabrice Laussy @fplaussy · 9 Sep 2024
𝗧𝘄𝗼 𝗣𝗵𝗼𝘁𝗼𝗻𝘀 𝗘𝘃𝗲𝗿𝘆𝘄𝗵𝗲𝗿𝗲
Part 4: The crème de la crème.
As promised earlier this year (part 1 here ), we collect the best snippets of our paper that the Royal Society published today. A fast way to read the paper:
Part 4: The crème de la crème.
As promised earlier this year (part 1 here ), we collect the best snippets of our paper that the Royal Society published today. A fast way to read the paper:
21 February (2024)
If you are remotely connected to quantum optics, and want to know what this is, follow this account, or wait 10 years that this becomes mainstream.
or join the Bavarian Illuminati for a workshop organized by Elena & Kai Müller in München on July 4, 5. Password: Fidelio.
Replying to @gabrielpeyre
"Radial spectrum" = "second-order coherence" in quantum optics - nature.com/articles/s4159…
20 February (2024)
Replying to @Kaju_Nut
Still Einstein never accepted to co-author a paper with Bose.
Replying to @amazingmap
Conclusion: la France, c'est l'Auvergne.
19 February (2024)
18 February (2024)
Replying to @TheCosmiChemist
Quelle perte, pour le monde; condoléances sincères.
16 February (2024)
Replying to @TEJINDER_TIFR and @martinmbauer
Peres, Rosen's student, will tell you about it for instance in Found. Phys., 35:511, 2005.
Sora: Obviously deranged creepy Orwellian character from the Ministry of Plans, rationalizing for young children a thermonuclear conflict that will wipe out the human race, unable to contain his maniac thirst for self-destruction, with the use of "Hunky Dory".
Replying to @martinmbauer
This article made Einstein never speak to Podolsky again.
Sora. What an age to live in... like when the ape took hold of the first broken femur to turn it into a tool. We can feel this frenzy of all the apes striking the walls of the cave in excitement of a new species-making technological revolution.
14 February (2024)
Replying to @JEnriqueVL and @srk_rodriguez
yes, I once suggested something like this myself, a sort of ELO rating of Referees, based on the long-term output accepted and rejected alike, including inflations of quotations for such jourdnals. But this proposal was also rejected when I applied to some editorial role in PRA.
13 February (2024)
Replying to @srk_rodriguez
PRL referees tend to confuse fundamental with trivial and novel with alien. Thanks "Physics Physique физика" existed as they' d had rejected Bell's paper for "not offering a significant advancement in the field" and asked "to include practical cases or experimental verification".
12 February (2024)
Replying to @Stella_Assange
Unfortunately, the rest of us must condemn this approach, however tempting and understandable it is for the one who is grieving. An abomination never makes up for another, even bigger one.
11 February (2024)
Replying to @InternetH0F
This typo on the fourth line of the list will be difficult to endure as time goes by.
Replying to @saragaza94 and @Sarah_Hassan94
Fils de César
Ou fils de rien
Tous les enfants
Sont comme le tien
Ou fils de rien
Tous les enfants
Sont comme le tien
Replying to @interesting_aIl
as long as it's laminar...
10 February (2024)
9 February (2024)
Replying to @InsiderWorld_1
Les bébés assassinés. Ils sont morts comme s'ils dormaient. Leur grace est immortelle. Mais son pyjama, où il était écrit papa, est devenu son linceul. Quelle honte pour tous ceux qui lui survivent.
Replying to @EnesOkullu
ve burada Dünya'da kalan kişiden bahsediyoruz
Winning or not the Nobel prize. Wikipedia page counts for Ekimov (top) and Arakawa (bottom).
Replying to @Paria4ever
Nothing escapes you dear Amir!
8 February (2024)
Replying to @CanalRiverTrust and @CRTWestMidlands
Beautiful.
There's a new cow-boy in town. Guess where I'm working now!
6 February (2024)
5 February (2024)
All photons are indistinguishable, but some are more indistinguishable than others. browse.arxiv.org/abs/2402.01627
4 February (2024)
Still on Twitter on a Sunday evening? Why not read an intimate "Behind the Paper" blog post at communities.springernature.com/posts/perfect-… for our latest paper @SciReports (with Sana) on what really makes a perfect single-photon source? There's also an after on my own blog: laussy.org/wiki/Blog:Scie…