Ciro Santilli @cirosantilli  40

 Articles (13k) Discussions (30) Comments (68) Follows  Received likes Files (694)

New Updated  Top  Announced  A-Z  Liked  Followed

Austria Updated 2025-07-16

 Read the full article

Mond Laboratory Updated 2026-08-21

 View more

cudl.lib.cam.ac.uk/view/PH-CAVENDISH-P-00822/1

 Read the full article

University of Cambridge laboratory Updated 2025-07-16

 Read the full article

History of the Josephson effect Updated 2025-07-16

 View more

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."

 Read the full article

Philip W. Anderson Updated 2025-07-16

 Read the full article

How to teach / Projects must aim for novelty Updated 2025-07-16

 View more

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.

 Read the full article

History of condensed matter physics Updated 2025-07-16

 View more

Bibliography:

 Read the full article

Handscroll Updated 2025-07-16

 View more

Ciro Santilli's favorite. A mixture of painting and book.

 Read the full article

Champaign-Urbana metropolitan area Updated 2025-07-16

 View more

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.

 Read the full article

Bilibili Updated 2025-07-16

 Read the full article

B4 Oxford physics course Updated 2025-07-16

 View more

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

 Read the full article

B2 Oxford physics course Updated 2025-07-16

 View more

www-thphys.physics.ox.ac.uk/people/AndreiStarinets/sr_mt_2022.html (archive) contains 2022 problem sets and notes, well done Mr Andrei Starinets!

 Read the full article

Quantum Software course of the University of Oxford Updated 2025-07-16

 View more

2022 page: www.cs.ox.ac.uk/teaching/courses/qsoft/ Half of the problems are Jupyter Notebooks, not bad.

Like Quantum Processes and Computation course of the University of Oxford, also ZX-calculus-heavy.

 Read the full article

Quantum Processes and Computation course of the University of Oxford Updated 2025-07-16

 View more

2022 page: www.cs.ox.ac.uk/teaching/courses/2022-2023/quantum/ (archive). Assignments are available:

2022 lecturer: Aleks Kissinger

The course would be better named ZX-calculus as it appears to be the only subject covered.

 Read the full article

Tensor product in quantum computing Updated 2025-07-16

 View more

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:

∣ 00 ⟩

that is the same as

∣ 0 ⟩ \otimes ∣ 0 ⟩

The tensor product is called a "product" because it distributes over addition.

E.g. consider:

(\frac{∣ 0 ⟩ + ∣ 1 ⟩}{2}) \otimes ∣ 0 ⟩ = \frac{∣ 0 ⟩ \otimes ∣ 0 ⟩ + ∣ 1 ⟩ \otimes ∣ 0 ⟩}{2} = \frac{∣ 00 ⟩ + ∣ 10 ⟩}{2}

(1)

Intuitively, in this operation we just put a Hadamard gate qubit together with a second pure

∣ 0 ⟩

qubit.

And the outcome still has the second qubit as always 0, because we haven't made them interact.

The quantum state

\frac{∣ 00 ⟩ + ∣ 10 ⟩}{2}

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:

\frac{∣ 00 ⟩ + ∣ 11 ⟩}{2} = \frac{∣ 0 ⟩ \otimes ∣ 0 ⟩ + ∣ 1 ⟩ \otimes ∣ 1 ⟩}{2}

(2)

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.

 Read the full article

Quantum state vector Updated 2025-07-16

 Read the full article

numpy/fft.py Updated 2025-07-16

 View more

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, $X_{k} = \overset{ˉ}{X_{N - k}}$ so there is redundancy in the. We also understand that rfft simply cuts off and only keeps half of the coefficients