@cirosantilli/_file/numpy/numpy/fft.py by Ciro Santilli 35 Updated +Created
Output:
sin(t)
fft
real 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10
rfft
real 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 0 0 0 0 0 0 0

sin(t) + sin(4t)
fft
real 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 -10 0 0 0 0 0 0 0 0 0 0 0 10 0 0 10
rfft
real 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 -10 0 0 0 0 0 0
With our understanding of the discrete Fourier transform we see clearly that:
  • the signal is being decomposed into sinusoidal components
  • because we are doing the Discrete Fourier transform of a real signal, for the fft, so there is redundancy in the. We also understand that rfft simply cuts off and only keeps half of the coefficients
Quantum state vector by Ciro Santilli 35 Updated +Created
Tensor product in quantum computing by Ciro Santilli 35 Updated +Created
We don't need to understand a super generalized version of tensor products to know what they mean in basic quantum computing!
Intuitively, taking a tensor product of two qubits simply means putting them together on the same quantum system/computer.
When we write the bra-ket notation: that is the same as .
The tensor product is called a "product" because it distributes over addition.
E.g. consider:
Intuitively, in this operation we just put a Hadamard gate qubit together with a second pure qubit.
And the outcome still has the second qubit as always 0, because we haven't made them interact.
The quantum state is called a separable state, because it can be written as a single product of two different qubits. We have simply brought two qubits together, without making them interact.
If we then add a CNOT gate to make a Bell state:
we can now see that the Bell state is non-separable: we've made the two qubits interact, and there is no way to write this state with a single tensor product. The qubits are fundamentally entangled.
B2 Oxford physics course by Ciro Santilli 35 Updated +Created
www-thphys.physics.ox.ac.uk/people/AndreiStarinets/sr_mt_2022.html (archive) contains 2022 problem sets and notes, well done Mr Andrei Starinets!
B4 Oxford physics course by Ciro Santilli 35 Updated +Created
www-pnp.physics.ox.ac.uk/~barra/teaching.shtml As of 2023, contains some good 2015 materials: web.archive.org/web/20220525094139/http://www-pnp.physics.ox.ac.uk/~barra/teaching.shtml It was called "Subatomic physics" back then.
2015 professor: Alan J. Barr.
Possible 2022 professor: Guy Wilkinson (unconfirmed): www.chch.ox.ac.uk/staff/professor-guy-wilkinson
Bilibili by Ciro Santilli 35 Updated +Created
Champaign-Urbana metropolitan area by Ciro Santilli 35 Updated +Created
It is quite comical that two separate towns were founded one next to the other right in the middle of nowhere. And that both have so slightly weird names.
Handscroll by Ciro Santilli 35 Updated +Created
Ciro Santilli's favorite. A mixture of painting and book.
Projects must aim for novelty by Ciro Santilli 35 Updated +Created
The projects you do must always aim to achieving some novel result.
You don't have to necessarily reach it. But you must aim for it.
Novel result can be taken broadly.
E.g., a new tutorial that explains something in a way never done before is novel.
But there must be something to your project that has never been done before.
You can start by reproducing other's work.
Philip W. Anderson by Ciro Santilli 35 Updated +Created
History of the Josephson effect by Ciro Santilli 35 Updated +Created
In 1962 Brian Josephson published his inaugural paper predicting the effect as Section "Possible new effects in superconductive tunnelling".
In 1963 Philip W. Anderson and John M. Rowell published their paper that first observed the effect as Section "Possible new effects in superconductive tunnelling".
Some golden notes can be found at True Genius: The Life and Science of John Bardeen page 224 and around. Philip W. Anderson commented:
We were all - Josephson, Pippard and myself, as well as various other people who also habitually sat at the Mond tea and participated in the discussions of the next few weeks - very much puzzled by the meaning of the fact that the current depends on the phase
As part of the course Anderson had introduced the concept of broken symmetry in superconductors. Josephson "was fascinated by the idea of broken symmetry, and wondered whether there could be any way of observing it experimentally."
University of Cambridge laboratory by Ciro Santilli 35 Updated +Created
Austria by Ciro Santilli 35 Updated +Created
Fugging, Upper Austria by Ciro Santilli 35 Updated +Created
Physics journal by Ciro Santilli 35 Updated +Created
The strongest are:
Paper by Brian Josephson by Ciro Santilli 35 Updated +Created

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