Lecture 4 | Quantum Entanglements, Part 1 (Stanford)

[jayejayeee]

great video thanks

[alexasmithy]

Very enjoyable thank you

[ttwilkable]

love the video man

[ttwilkable]

good work here

[ericajjful]

great video thanks

[shellybirdy]

Very enjoyable thank you

[SuperDogbrown]

interesting video and very informative

[adelle0001]

nice one!

[grunder20]

very complex discussion!

[NewagehegelianLiam]

Where's the download link?

[agapitoflores001]

I guess going to Stanford will be very much difficult for me.

[TheGuyWhoToldMeToTel]

I would recommend watching these lectures in order. To view the correct order wikipedia "Susskind" and the order is on his page.

I would also recommend not using this course to prepare for a master's course in QM. Your time is better spent learning basic Hamiltonian mechanics and complex analysis if you plan on taking QM in the near future. This is still a great way to learn general concepts though.

Pursue this field, it will change your fucking world.

[Ferrus91]

Like 11 year olds indeed.

[Pyenot421]

All this stuff makes me regret crash-and-burning my mathematics masters even more :(

[whactya]

How does one deduce the proper Hermitian operator to represent a given measurement?

[HomemadeBanjo]

@whactya, Susskind is just skimming over the math to make it more digestible, so the fundamental basis is missing here. If you really want to understand it well enough to actually construct the operators you will need to get a textbook like DJ Griffiths 'Introduction to Quantum Mechanics second edition' and be prepared to spend a day (or a week!) on each of the 450+ pages.

[sayedzeeshan]

@whactya Well you have to do it by using concepts from matrix spaces. The matrices have to be unitary.

[san34451]

Does anyone know where to find "Quantum Entanglements, Part 2"? Was it video-recorded? Only Part 1 and Part 3 are available on YouTube. StanfordUniversity did clarify that Part 2 "is unavailable at this time", but that was an year ago.

[jonydude]

Wanna know the sad thing? I'm loving this video, and I'm a car detailer! I swear! I'm like the garbage collector on Dilbert!

[polymath7]

@jonydude 

That's anything but sad; it's the most heartening thing I've read or heard in at least in a month.

[geoffreyah]

Thankyou @ArcaneInquisitor I will dust off my college algebra book, notes and binder and maybe take a course if necessary. I haven't done algebra in a while but I like quantum physics.

[geoffreyah]

What is a complex conjegate? What kind of math does one need to know to understand this math? I had beginning and intermediate algrebra

[getisboy]

@geoffreyah A complex number is in the form a+bi. a and b are constants and i is the square root of -1. The complex conjugate of a number is a-bi, so for a real number it's just the number itself.

[ArcaneInquisitor]

@geoffreyah That math here is primarily linear algebra. Any first or second year level university course on elementary linear algebra should set you up with everything he is doing here. And linear algebra doesn't require you to have a strong background in pre-cal so anyone should be able to give it a shot.

[MrAytug]

that bottle could be perrier or vine and first two lecture could be vodka or cofee in the cup. u cnnot know the ingredients unless u try to taste. its a quantum thing hahahaha. and the result can ALTER your grade state LOL. GREAT PROFESSOR!!!

[andrew11235]

So sigma is a 3rd-order tensor, right? It has components sigma 1, sigma 2 and sigma 3, all of which are matrices.

[luzzie9]

@andrew11235 The sigma are operators which operate on spinors, the two-dimensional equivalents of tensors.

[luzzie9]

The sigmas are two dimensional because they operate on the representational space of the spin vectors which, as APoudy points out, is two dimensional. You need three to generate the physical space of the spinning particle.

[luzzie9]

If the sigma matrices are applied to spin in three dimensional space, why aren't they 3x3 matrices?

[APoudy]

The point is that the dimention of sigma matrices has to do with the uantity of eigenvectors only. Up and down are the two distinct eigenvectors of observable, they're orthogonal, two distinct output of any measurements, and the way to express it in quantum theory is to have 2x2 Hermitian operators.

[jad0halimeh]

spin is a 3 dimensional physical quantity. however, unlike momentum or position, you can only measure spin along one direction. Along that direction, your spin is either up or down, i.e. your measurement yields one of two possible results, making the state space of spin 2D, thus why your sigmas are 2-dimensional. These matrices are really nothing but the operator (spin component along a direction) expressed in terms of the Eigenstates of some operator (usaully Sz).

[Grundalizer]

nice he lectures with a bottle of champagne, he's a baller

[ibreakkidslegs]

why do you comment the same thing a week apart?

[JohnEdwardIAF]

nevertheless has some issues with susskind. I don't know what it is, but it's probably because susskind is a non-believer. Youtube videos with susskind are full of haters.

[foketesz]

what a GREAT teacher. The fact that such a cutting-edge scientist as Mr. Susskind should recognize the importance of taking the risk and time of teaching speaks wonders about his intentions regarding the search for the truth. And that's not the impression I used to get from him before seeing these lectures. A great mind.

[timcabc]

I don't get it, why would it take 6 independent real variable to characterize a pair of electron?

[DavidAKZ]

3 for one electron in the 'n' direction. 3 for the other electron in the 'm' direction.

[philymou]

Hello grandpa,you're so funny.

[shon9514]

Pooppepper, before being concerned about peoples sexuality, although it is irrelevant and no business of yours,grammar class might be a good start. Btw, since you act it, are you homophobic? Maybe you are gay and don't know it yet, hence your stage name. Oh, yes, I'm straight fyi.

[polymath7]

I notice, in returning to this video, that I have received three "thumbs down" for pointing out that I am being impersonated.

To be sure, one can get only so exercised over the tarnished reputation of a faceless screen name on Youtube; but the "thumbs down" still strike me as curious.

[polymath7]

This sort of thing is why my television has not been plugged in for several weeks (and I'm not saying that to sound intelligent).

Who'd have thought Youtube would turn out to be an autodidact's dream?

You can use it to watch a video of a lemur picking its nose, or you can use it to watch stuff like this. :)

[crankatorium]

@polymath7 with a name like "polymath," you're definitely trying to sound intelligent.

[De4sher]

@polymath7 lemur picking its nose yeah! where see?

[polymath7]

@De4sher

This was just a hypothetical (if entirely plausible) example of the type of witless mind pollution one finds on the "most watched" page. There is no such video as far as I'm aware.

But don't despair.

There is a video of an orangutan pissing in its own mouth.

[De4sher]

@polymath7 yeah and that was just an example of plausible illiterate response to your description of hypothetical situations.

but ima look for that orangutan.

[tupatupa89]

sooo cool, i saw the entire video...although i didn't get much.

[kamyarghofrani]

you would get it if you watch it from the begining.

i made a play list of them.

just search my user and you will get it :)

[pikachun00b7]

His students are in their 40s.

[marianiiina]

what? really??????

[polymath7]

(shrug) Why not? For that matter, why not smoke a joint while teaching?

[AtomosNucleous]

well this could make quantum entanglements lectures an even higher intelectual experience

[DavidAKZ]

It's supposed to represent the spin of an electron

[twiddle7125]

Gotta love that starbux chugging sound lol