Ciro Santilli @cirosantilli 37

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Primality test Updated 2025-07-16

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Primer (YouTube channel) Updated 2025-07-16

This channel contains several 2D continuous simulations and explains AI techniques used.

The engine appears to be open source: github.com/Primer-Learning/PrimerTools (previously at: github.com/Helpsypoo/primer). Models are closed source however.

They have several interesting multiagent game ideas.

Claims Unity-based, so has the downside of relying on a non-FOSS engine.

Ciro became mildly jealous of this channel when he found out about it, because at 800k subscribers at the time, the creator is likely able to make a living off of it, something which Ciro thought impossible.

As of 2022 he was at 1.6M followers with only 17 videos! Of course, much of those videos is about the software and they require infinite development hours to video time ratios.

Much of this success hinges a large part on the amazing 3D game presentation.

Well done!

Created by Justin Helps. Awesome name.

To make things better, the generically named channel is also the title of one of the best films of al time: Primer (2004).

Simulating Foraging Decisions by Primer (2020)

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Probable observation of the Josephson superconducting tunneling effect Updated 2025-07-16

Paper by Philip W. Anderson and John M. Rowell that first (?) experimentally observed the Josephson effect.

Paywalled by the American Physical Society as of 2023 at: journals.aps.org/prl/abstract/10.1103/PhysRevLett.10.230

DOI: doi.org/10.1103/PhysRevLett.10.230

TODO understand the graphs in detail.

They used tin-oxide-lead tunnel at 1.5 K. TODO oxide of what? Why two different metals? They say that both films are 200 nm thick, so maybe it is:

   -----+------+------+-----
...  Sn | SnO2 | PbO2 | Pb  ...
   -----+------+------------
          100nm 100nm

A reconstruction of their circuit in Ciro's ASCII art circuit diagram notation TODO:

DC---R_10---X---G

There are not details of the physical construction of course. Reproducibility lol.

Figure 1.
Figure 1 of Probable observation of the Josephson superconducting tunneling effect
. TODO what do the dotted lines mean?

Figure 2.
Figure 2 of Probable observation of the Josephson superconducting tunneling effect
.

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Product definition of the exponential function Updated 2025-07-16

e^{x} = lim_{n \to \infty} (1 + \frac{x}{n})^{n}

The basic intuition for this is to start from the origin and make small changes to the function based on its known derivative at the origin.

More precisely, we know that for any base b, exponentiation satisfies:

$b^{x + y} = b^{x} b^{y}$ .
$b^{0} = 1$ .

And we also know that for

b = e

in particular that we satisfy the exponential function differential equation and so:

\frac{d e ^{x}}{d x} (0) = 1

One interesting fact is that the only thing we use from the exponential function differential equation is the value around

x = 0

, which is quite little information! This idea is basically what is behind the importance of the ralationship between Lie group-Lie algebra correspondence via the exponential map. In the more general settings of groups and manifolds, restricting ourselves to be near the origin is a huge advantage.

Now suppose that we want to calculate

e^{1}

. The idea is to start from

e^{0}

and then then to use the first order of the Taylor series to extend the known value of

e^{0}

to

e^{1}

.

E.g., if we split into 2 parts, we know that:

e^{1} = e^{1/2} e^{1/2}

or in three parts:

e^{1} = e^{1/3} e^{1/3} e^{1/3}

so we can just use arbitrarily many parts

e^{1/ n}

that are arbitrarily close to

x = 0

:

e^{1} = (e^{1/ n})^{n}

and more generally for any

x

we have:

e^{x} = (e^{x / n})^{n}

Let's see what happens with the Taylor series. We have near

y = 0

in little-o notation:

e^{y} = 1 + y + o (y)

Therefore, for

y = x / n

, which is near

y = 0

for any fixed

x

:

e^{x / n} = 1 + x / n + o (1/ n)

and therefore:

e^{x} = (e^{x / n})^{n} = (1 + x / n + o (1/ n))^{n}

which is basically the formula tha we wanted. We just have to convince ourselves that at

lim_{n \to \infty}

, the

o (1/ n)

disappears, i.e.:

(1 + x / n + o (1/ n))^{n} = (1 + x / n)^{n}

To do that, let's multiply

e^{y}

by itself once:

e^{y} e^{y} = (1 + y + o (y)) (1 + y + o (y)) = 1 + 2 y + o (y)

and multiplying a third time:

e^{y} e^{y} e^{y} = (1 + 2 y + o (y)) (1 + y + o (y)) = 1 + 3 y + o (y)

TODO conclude.

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Program Raspberry Pi Pico W with C Updated 2025-07-26

Ubuntu 22.04 build just worked, nice! Much feels much cleaner than the Micro Bit C setup:

sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib

git clone https://github.com/raspberrypi/pico-sdk
cd pico-sdk
git checkout 2e6142b15b8a75c1227dd3edbe839193b2bf9041
cd ..

git clone https://github.com/raspberrypi/pico-examples
cd pico-examples
git checkout a7ad17156bf60842ee55c8f86cd39e9cd7427c1d
cd ..

export PICO_SDK_PATH="$(pwd)/pico-sdk"
cd pico-exampes
mkdir build
cd build
# Board selection.
# https://www.raspberrypi.com/documentation/microcontrollers/c_sdk.html also says you can give wifi ID and password here for W.
cmake -DPICO_BOARD=pico_w ..
make -j

Then we install the programs just like any other UF2 but plugging it in with BOOTSEL pressed and copying the UF2 over, e.g.:

cp pico_w/blink/picow_blink.uf2 /media/$USER/RPI-RP2/

Note that there is a separate example for the W and non W LED, for non-W it is:

cp blink/blink.uf2 /media/$USER/RPI-RP2/

Also tested the UART over USB example:

cp hello_world/usb/hello_usb.uf2 /media/$USER/RPI-RP2/

You can then see the UART messages with:

screen /dev/ttyACM0 115200

TODO understand the proper debug setup, and a flash setup that doesn't require us to plug out and replug the thing every two seconds. www.electronicshub.org/programming-raspberry-pi-pico-with-swd/ appears to describe it, with SWD to do both debug and flash. To do it, you seem need another board with GPIO, e.g. a Raspberry Pi, the laptop alone is not enough.

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Program the Micro Bit in C Updated 2025-07-27

stackoverflow.com/questions/73877965/how-to-compile-c-c-code-into-a-hex-file-for-the-bbc-microbit

Official support is abysmal, very focused on MicroPython and their graphical UI.

The setup impossible to achieve as it requires setting up the Yotta, just like the impossible to setup Compile MicroPython code for Micro Bit locally on Ubuntu 22.04 with your own firmware setup.

So we just use github.com/lancaster-university/microbit-samples + github.com/carlosperate/docker-microbit-toolchain:

docker pull ghcr.io/carlosperate/microbit-toolchain:latest
git clone https://github.com/lancaster-university/microbit-samples
cd microbit-samples
git checkout 285f9acfb54fce2381339164b6fe5c1a7ebd39d5

# Select a sample, builds one at a time. The default one is the hello world.
cp source/examples/hello-world/* source

# Build and flash.
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest yotta build
cp build/bbc-microbit-classic-gcc/source/microbit-samples-combined.hex "/media/$USER/MICROBIT/"

.hex file size for the hello world was 447 kB, much better than the MicroPython hello world downloaded from the website which was about 1.8 MB!

If you try it again for a second time from a clean tree, it fails with:

warning: github rate limit for anonymous requests exceeded: you must log in

presumably because after Yotta died it started using GitHub as a registry... sad. When will people learn. Apparently we were at 5000 API calls per hour. But if you don't clean the tree, you will be just fine.

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PsiQuantum founding myth Updated 2025-07-16

Once upon a time, the British Government decided to invest some 80 million into quantum computing.

Jeremy O'Brien told his peers that he had the best tech, and that he should get it all.

Some well connected peers from well known universities did not agree however, and also bid for the money, and won.

Jeremy was defeated. And pissed.

So he moved to Palo Alto and raised a total of $665 million instead as of 2021. The end.

Makes for a reasonable the old man lost his horse.

www.ft.com/content/afc27836-9383-11e9-aea1-2b1d33ac3271 British quantum computing experts leave for Silicon Valley talks a little bit about them leaving, but nothing too juicy. They were called PsiQ previously apparently.

The departure of some of the UK’s leading experts in a potentially revolutionary new field of technology will raise fresh concerns over the country’s ability to develop industrial champions in the sector.

More interestingly, the article mentions that this was party advised by early investor Hermann Hauser, who is known to be preoccupied about UK's ability to create companies. Of course, European Tower of Babel.

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Public domain scientific paper by year Updated 2025-07-16

Here we list public domain academic papers. They must be public domain in the country of origin, not just the US, which had generally less stringent timings with the 95 year after publication rule rather than life + 70, which often ends up being publication + 110/120. Once these are reached, they may be upload to Wikimedia Commons!

2018
- Max Planck's works in Germany (1947 + 70)
  - 1900: Zur Theorie des Gesetzes der Energieverteilung im Normalspectrum
  - Wikimedia Commons category: commons.wikimedia.org/wiki/Category:Works_by_Max_Planck
2026
- Albert Einstein's works in Germany (1955 + 70)
2031:
- Max von Laue's works in Germany (1960 + 70)
  - 1912: Interferenz-Erscheinungen bei Röntgenstrahlen (Interference phenomena in X-rays). Scan: archive.org/details/sitzungsberichte1912knig/page/n393/mode/2up. Clean upload: archive.org/details/interferenz-erscheinungen-bei-rontgenstrahlen
2032:
- Erwin Schrödinger works in Germany (1961 + 70)
  - 1926: Quantization as an Eigenvalue Problem. Scan: ia903403.us.archive.org/29/items/sim_annalen-der-physik_1926_79_contents/sim_annalen-der-physik_1926_79_contents.pdf. Clean upload: archive.org/details/quantisierung-als-eigenwertproblem
2042
- 1927: www.nature.com/articles/119558a0 The Scattering of Electrons by a Single Crystal of Nickel. (1971 + 70), Germer's death. Scan: archive.org/details/sim_nature-uk_1927-04-16_119_2998/page/554/mode/2up. Clean upload: archive.org/details/the-scattering-of-electrons-by-a-single-crystal-of-nickel. The Davisson-Germer experiment!
2049
- 1922 Stern-Gerlach experiment papers such as The experimental proof of directional quantization in the magnetic field. Stern died in 1969, Gerlach died in 1979, so 1979 + 70
2056
- 1961 Experimental Evidence for Quantized Flux in Superconducting Cylinders. Published in the US, so 1961 + 95.

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Public relations Updated 2025-07-16

The reason public relations is evil in modern society is because, like discrimination, public relations works by dumb association and not logic or fairness.

If you're the son of the killer, you're fucked.

This is unlike our ideal for law which attempts, though sometimes fails, at isolating cause and effect.

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Single electron double slit experiment Updated 2025-07-16

Electron Interference by the Italian National Research Council (1976)

Institutional video about the 1974 single electron experiment by Merli, Missiroli, Pozzi from the University of Bologna.

Uses an electron biprism as in electron holography inside a transmission electron microscope.

Shows them manually making the biprism by drawing a fine glass wire and coating it with gold.

Then actually show the result live on a television screen, where you see the interference patterns only at higher electron currents, and then on photographic film.

This was elected "the most beautiful experiment" by readers of Physics World in 2002.

Accompanying website: l-esperimento-piu-bello-della-fisica.bo.imm.cnr.it/english/index.html.

Italian title: "Interferenza di elettroni". Goddammit, those Italian cinematographers can make even physics look exciting!

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Quantization as an Eigenvalue Problem Updated 2025-07-16

This paper appears to calculate the Schrödinger equation solution for the hydrogen atom.

TODO is this the original paper on the Schrödinger equation?

Published on Annalen der Physik in 1926.

Open access in German at: onlinelibrary.wiley.com/doi/10.1002/andp.19263840404 which gives volume 384, Issue 4, Pages 361-376. Kudos to Wiley for that. E.g. Nature did not have similar policies as of 2023.

This paper may have fallen into the public domain in the US in 2022! On the Internet Archive we can see scans of the journal that contains it at: ia903403.us.archive.org/29/items/sim_annalen-der-physik_1926_79_contents/sim_annalen-der-physik_1926_79_contents.pdf. Ciro Santilli extracted just the paper to: commons.wikimedia.org/w/index.php?title=File%3AQuantisierung_als_Eigenwertproblem.pdf. It is not as well processed as the Wiley one, but it is of 100% guaranteed clean public domain provenance! TODO: hmmm, it may be public domain in the USA but not Germany, where 70 years after author deaths rules, and Schrodinger died in 1961, so it may be up to 2031 in that country... messy stuff. There's also the question of wether copyright is was tranferred to AdP at publication or not.

An early English translation present at Collected Papers On Wave Mechanics by Deans (1928).

Contains formulas such as the Schrödinger equation solution for the hydrogen atom (1''):

(\frac{\partial ψ}{\partial x})^{2} + (\frac{\partial ψ}{\partial y})^{2} + (\frac{\partial ψ}{\partial z})^{2} + \frac{2 m}{K} (E + \frac{2}{r}) ψ^{2} = 0

where:

$r = x^{2} + y^{2} + z^{2}$
In order for there to be numerical agreement, $K$ must have the value $h /2 π$
$e$ , $m$ are the charge and mass of the electron

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Quantum algorithm Updated 2025-07-16

This is the true key question: what are the most important algorithms that would be accelerated by quantum computing?

Some candidates:

Shor's algorithm: this one will actually make humanity worse off, as we will be forced into post-quantum cryptography that will likely be less efficient than existing classical cryptography to implement
quantum algorithm for linear systems of equations, and related application of systems of linear equations
Grover's algorithm: speedup not exponential. Still useful for anything?
Quantum Fourier transform: TODO is the speedup exponential or not?
Deutsch: solves an useless problem
NISQ algorithms

Do you have proper optimization or quantum chemistry algorithms that will make trillions?

Maybe there is some room for doubt because some applications might be way better in some implementations, but we should at least have a good general idea.

However, clear information on this really hard to come by, not sure why.

Whenever asked e.g. at: physics.stackexchange.com/questions/3390/can-anybody-provide-a-simple-example-of-a-quantum-computer-algorithm/3407 on Physics Stack Exchange people say the infinite mantra:

Lists:

Quantum Algorithm Zoo: the leading list as of 2020
quantum computing computational chemistry algorithms is the area that Ciro and many people are te most excited about is
cstheory.stackexchange.com/questions/3888/np-intermediate-problems-with-efficient-quantum-solutions
mathoverflow.net/questions/33597/are-there-any-known-quantum-algorithms-that-clearly-fall-outside-a-few-narrow-cla

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Quantum chromodynamics Updated 2025-07-16

Formulated as a quantum field theory.

Quarks, Gluon flux tubes, Strong Nuclear Force, & Quantum Chromodynamics by Physics Videos by Eugene Khutoryansky (2018)

Source. Some decent visualizations of how the field lines don't expand out like they do in electromagnetism, suggesting color confinement.

PHYS 485 Lecture 6: Feynman Diagrams by Roger Moore (2016)

Source. Despite the title, this is mostly about QCD.

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Quantum circuits vs classical circuits Updated 2025-07-16

Just like a classic programmer does not need to understand the intricacies of how transistors are implemented and CMOS semiconductors, the quantum programmer does not understand physical intricacies of the underlying physical implementation.

The main difference to keep in mind is that quantum computers cannot save and observe intermediate quantum state, so programming a quantum computer is basically like programming a combinatorial-like circuit with gates that operate on (qu)bits:

For this reason programming a quantum computer is much like programming a classical combinatorial circuit as you would do with SPICE, verilog-or-vhdl, in which you are basically describing a graph of gates that goes from the input to the output

For this reason, we can use the words "program" and "circuit" interchangeably to refer to a quantum program

Also remember that and there is no no clocks in combinatorial circuits because there are no registers to drive; and so there is no analogue of clock in the quantum system either,

Another consequence of this is that programming quantum computers does not look like programming the more "common" procedural programming languages such as C or Python, since those fundamentally rely on processor register / memory state all the time.

Quantum programmers can however use classic languages to help describe their quantum programs more easily, for example this is what happens in Qiskit, where you write a Python program that makes Qiskit library calls that describe the quantum program.

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Quantum Computation and Quantum Information by Nielsen and Chuang Updated 2025-07-16

www.amazon.com/dp/1107002176

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Quantum computer benchmark Updated 2025-07-16

One important area of research and development of quantum computing is the development of benchmarks that allow us to compare different quantum computers to decide which one is more powerful than the other.

Ideally, we would like to be able to have a single number that predicts which computer is more powerful than the other for a wide range of algorithms.

However, much like in CPU benchmarking, this is a very complex problem, since different algorithms might perform differently in different architectures, making it very hard to sum up the architecture's capabilities to a single number as we would like.

The only thing that is directly comparable across computers is how two machines perform for a single algorithm, but we want a single number that is representative of many algorithms.

For example, the number of qubits would be a simple naive choice of such performance predictor number. But it is very imprecise, since other factors are also very important:

qubit error rate
coherence time, which determines the maximum circuit depth
qubit connectivity. Can you only connect to 4 neighbouring qubits in a 2D plane? Or to every other qubit equally as well?

Quantum volume is another less naive attempt at such metric.

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Quantum computers as experiments that are hard to predict outcomes Updated 2025-07-16

One possibly interesting and possibly obvious point of view, is that a quantum computer is an experimental device that executes a quantum probabilistic experiment for which the probabilities cannot be calculated theoretically efficiently by a nuclear weapon.

This is how quantum computing was originally theorized by the likes of Richard Feynman: they noticed that "Hey, here's a well formulated quantum mechanics problem, which I know the algorithm to solve (calculate the probability of outcomes), but it would take exponential time on the problem size".

The converse is then of course that if you were able to encode useful problems in such an experiment, then you have a computer that allows for exponential speedups.

This can be seen very directly by studying one specific quantum computer implementation. E.g. if you take the simplest to understand one, photonic quantum computer, you can make systems for which you need exponential time to calculate the probabilities that photons will exit through certain holes and not others.

The obvious aspect of this idea is by coming from quantum logic gates are needed because you can't compute the matrix explicitly as it grows exponentially: knowing the full explicit matrix is impossible in practice, and knowing the matrix is equivalent to knowing the probabilities of every outcome.

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Quantum computing Updated 2025-07-16

Quantum is getting hot in 2019, and even Ciro Santilli got a bit excited: quantum computing could be the next big thing.

No useful algorithm has been economically accelerated by quantum yet as of 2019, only useless ones, but the bets are on, big time.

To get a feeling of this, just have a look at the insane number of startups that are already developing quantum algorithms for hardware that doesn't/barely exists! quantumcomputingreport.com/players/privatestartup (archive). Some feared we might be in a bubble: Are we in a quantum computing bubble?

To get a basic idea of what programming a quantum computer looks like start by reading: Section "Quantum computing is just matrix multiplication".

Some people have their doubts, and that is not unreasonable, it might truly not work out. We could be on the verge of an AI winter of quantum computing. But Ciro Santilli feels that it is genuinely impossible to tell as of 2020 if something will work out or not. We really just have to try it out and see. There must have been skeptics before every single next big thing.

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Quantum Computing Inc. Updated 2025-10-14

Really weird and obscure company, good coverage: thequantuminsider.com/2020/02/06/quantum-computing-incorporated-the-first-publicly-traded-quantum-computing-stock/

Publicly traded in 2007, but only pivoted to quantum computing much later.

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Quantum dot Updated 2025-07-16

TODO WTF is this? How is it built? What is special about it?

Mentioned a lot in the context of superconducting quantum computers, e.g. youtu.be/t5nxusm_Umk?t=268 from Video "Quantum Computing with Superconducting Qubits by Alexandre Blais (2012)",

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