Magatzem Mecànica Quàntica

Magatzem Mecànica Quàntica

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Feynman explica l’experiment de la doble escletxa
MQ i llum polaritzada (vídeo divulgatiu 3blue1brown)
Some light quantum mechanics (with minutephysics)
The math of superposition and quantum states. Minutephysics channel: https://www.youtube.com/user/minutephysics Help fund future projects: https://www.patreon.com/3blue1brown This video was sponsored by Brilliant: https://brilliant.org/3b1b An equally valuable form of support is to simply share some of the videos. Special thanks to these supporters: http://3b1b.co/light-quantum-thanks Huge thanks to my friend Evan Miyazono, both for encouraging me to do this project, and for helping me understand many things along the way. This is a simple primer for how the math of quantum mechanics, specifically in the context of polarized light, relates to the math of classical waves, specifically classical electromagnetic waves. I will say, if you *do* want to go off and learn the math of quantum mechanics, you just can never have too much linear algebra, so check out the series I did at https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2xVFitgF8hE_ab Mistakes: As several astute commenters have pointed out, the force arrow is pointing the wrong way at 2:18. Thanks for the catch! *Note on conventions: Throughout this video, I use a single-headed right arrow to represent the horizontal direction. The standard in quantum mechanics is actually to use double-headed arrows for describing polarization states, while single-headed arrows are typically reserved for the context of spin. What's the difference? Well, using a double-headed arrow to represent the horizontal direction emphasizes that in a quantum mechanical context, there's no distinction between left and right. They each have the same measurable state: horizontal (e.g. they pass through horizontally oriented filters). Once you're in QM, these kets are typically vectors in a more abstract space where vectors are not necessarily spatial directions but instead represent any kind of state. Because of how I chose to motivate things with classical waves, where it makes sense for this arrow to represent a unit vector in the right direction, rather than the more abstract idea of a horizontal state vector, I chose to stick with the single-headed notation throughout, though this runs slightly against convention. Music by Vincent Rubinetti: https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe, and click the bell to receive notifications (if you're into that). If you are new to this channel and want to see more, a good place to start is this playlist: http://3b1b.co/recommended Various social media stuffs: Website: https://www.3blue1brown.com Twitter: https://twitter.com/3Blue1Brown Patreon: https://patreon.com/3blue1brown Facebook: https://www.facebook.com/3blue1brown Reddit: https://www.reddit.com/r/3Blue1Brown
Some light quantum mechanics (with minutephysics)
Some cooking recipes on quantum mechanics (apunts introductoris)
Nsq

Recursos que poden ser útils

Stern-Gerlach introducció històrica de l’experiment (bastant decent)
Video preview
Video preview
Minut 8:00 —> matrius de Pauli
A quick trick for computing eigenvalues | Chapter 15, Essence of linear algebra
How to write the eigenvalues of a 2x2 matrix just by looking at it. Need a refresher on eigenvalues? https://youtu.be/PFDu9oVAE-g Thanks to Tim for the jingle: https://www.youtube.com/acapellascience Help fund future projects: https://www.patreon.com/3blue1brown​ An equally valuable form of support is to simply share the videos. Special thanks to these supporters: https://3b1b.co/quick-eigen-thanks Lockdown math lecture talking about the mean product formula: https://youtu.be/MHXO86wKeDY Timestamps: 0:00 - Background 4:53 - Examples 10:24 - Relation to the characteristic polynomial 12:00 - Last thoughts ------------------ These animations are largely made using a custom python library, manim. See the FAQ comments here: https://www.3blue1brown.com/faq#manim https://github.com/3b1b/manim https://github.com/ManimCommunity/manim/ You can find code for specific videos and projects here: https://github.com/3b1b/videos/ Music by Vincent Rubinetti. https://www.vincentrubinetti.com/ Download the music on Bandcamp: https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown Stream the music on Spotify: https://open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe: http://3b1b.co/subscribe Various social media stuffs: Website: https://www.3blue1brown.com Twitter: https://twitter.com/3blue1brown Reddit: https://www.reddit.com/r/3blue1brown Instagram: https://www.instagram.com/3blue1brown_animations/ Patreon: https://patreon.com/3blue1brown Facebook: https://www.facebook.com/3blue1brown
A quick trick for computing eigenvalues | Chapter 15, Essence of linear algebra
Descarregar el projecte sencer i executar main.py

Playlists formalisme matemàtic

Operador evolució temporal
Altres PDFs

Screenshots

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Extra

Emergència d’objectes clàssics

Imaginem que tenim una xarxa de partícules amb spin i tenim de l’ordre de
Cada punt de la xarxa seria un espai de Hilbert de dimensió 2.
Aleshores
Aleshores a mida que augmentem el nombre de partícules la incertesa augmenta com a 1/ arrel quadrada de N.
I a partir de físic estadística, el model de Ising, es pot arribar a que la penalització al augmentar el nombre de partícules realment és cosa que implica que és literalment zero (no hi ha incertesa).

Oscil·lador Harmònic

Tot són operadors ()
Algunes propietats
Bla bla [no m’ha donat temps, algo rollo i més coses]
Normalització
I per tant
Expressions matricials dels operadors quan estem en la base
Tenim que o que
Operador moment i tal
Ja ens podem imaginar les matrius que serien (en la base |n>)
 

El límits clàssic, estats coherents

Per tenim
En el límit clàssic i
Teorema d’Ehrenfest (es compleix per qualsevol estat)
Per —> .
“Energia més gran segur que és clàssic” Incorrecte. Ser més gran o tenir més energia no implica no ser quàntica (superconductors, etc.). Té més a veure amb l’acció.” En el límit clàssic no es comporta com un oscil·lador clàssic.
Nota, ara i (minúscules) són les variables clàssiques, no pas operadors.
Si obtenim
En el límit clàssic .
Mirem
Recordem
Si
Bla bla bla
A partir de (1) i (2) volem veure que
Ns com arribem a
Determinació de
Bla bla
I també
I arribem a
 

Matrius de Pauli i tensors de rang 3

Tensors de rang 3

Matrius de Pauli

Propietats
En forma indicial
Nota
Si escrivim estem fent referència a un vector de matrius és a dir un tensor de rang 3
Bla bla
Més propietats
I per tant
Al mateix temps

Coeficients de Clebsch Gordan

Video preview
Video preview

Demos vàries que poden caure a les qüestions

Recopilar-les d’exàmens d’anys anteriors

Sistemes compostos

Exemple

Enunciat
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Solució
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