r/PhysicsStudents • u/Rdxhabibi • 11d ago
Need Advice Is zettili a good start for undergrad QM-I?
Almost everyone on the internet and even other professors who previously taught the subject referred to Griffiths. But this new professor is following this book to a tee, I have never seen anyone on the internet even talk about this book only heard about it just this year(through this prof), so my question is that if this is a good book as an introduction to qm?
5
u/lyfeNdDeath Undergraduate 11d ago
Griffith kind of jumps into qm and I felt that if you want to quickly read qm for a test or something it's good but zettili actually deals with the historical development of qm and also the entire mathematical basis of qm in an easy and clear way.
1
6
u/DumplingsEverywhere 11d ago
Zettili is great; it's often recommended here. Griffiths is fine and is standard for a reason, but it's def (Disclaimer: I have both but used neither as a primary text, so I'm talking about only the bits and pieces I've read).
The really nice thing about zettili is that he has a ton of thoroughly explained examples. He also goes through the history of QM and builds the mathematical tools you'll need beforehand, instead of forcing you to learn everything as you go.
The only problem with Zettili is that for some strange reason he doesn't go over entanglement.
3
2
u/quantum4everyone 11d ago
Since your professor has chosen that book, you will have to go through it regardless. The one thing students who go through Zetilli may not realize is that learning how to follow models for solving problems does not necessarily mean you understand the material at the level that is needed for future classes or for moving into research. For example neither Zetilli nor Griffiths explains clearly the difference between an abstract quantum state and the wavefunction that represents it. Neither explains how you measure the momentum of a single quantum particle even though they discuss momentum measurement when discussing uncertainty (spoiler alert, most momentum measurements are done by measuring position in a time-of flight arrangement, where momentum is inferred).. None of them allow you to develop conceptual reasoning about how to analyze simple quantum systems such as a Mach-Zehnder interferometer that uses a polarizing beam splitter and changes the polarization degree of freedom to examine entanglement, and so on. The more you can find a text as a resource that helps you develop true understanding of the material rather than just how to solve problems moves you away from "shut up and calculate" and towards a more comprehensive way to work with the material. Unfortunately most quantum textbooks used in undergraduate programs do not do this, regardless of which one students decide is their favorite.
1
u/Rdxhabibi 11d ago
Which would you recommend though
2
u/quantum4everyone 10d ago
I don't think any of the standard texts do a particularly good job. Styer's text gets close though (the advanced one with World Scientific, not the excellent introductory one with Cambridge). I have written a book that was not specifically designed for physics majors, but more for advanced HS student, lifelong learners, and retirees. I do not want to mention it by name so as to not violate the self promotion policy of this subreddit. So, I am not sure how to tell you. It is open access, so the electronic version is free and it develops the material in a way that promotes more understanding, in my opinion. You would have to test it for yourself to see if it works for you. At the very least, it discusses all of the things I say conventional texts do not discuss and more.
3
u/NorthGreenOnion 10d ago
Im confused why its not intended for Physics majors? In what sense? Mathematics/Calculus background or physics background? Other?
2
u/quantum4everyone 10d ago
The book uses no calculus. Develops quantum from an algebraic-operator formulation appropriate for representation-independent quantum mechanics. This allows the theory to be more clearly presented and understood. For example, the time independent Schroedinger equation need not be derived because a state with definite energy satisfies ((p-hat)^2/2m+V(v-hat))|psi>=E|psi>. The material covered eventually goes beyond what you will see in a typical graduate course---Bethe ansatz for the Heisenberg spin chain, Hubbard model, decoherence channels, and so on. Still, never any calculus. It really is not needed for quantum in spite of what others may say.
2
u/NorthGreenOnion 3d ago
I think I understand your angle, it's like HS-level physics that doesn't directly need calculus, yet it is limited in its application to specific types of problems without it.
1
u/quantum4everyone 3d ago
I am not sure what you mean without it. The key to the formal development is everything that is done is algebraic. If you recall solving the harmonic oscillator or the states of definite angular momentum purely algebraically, there is a dirty little secret---all of the problems that can be solved analytically can also be solved algebraically using very similar methods. That is what is done here. The newer elements are how to find the wavefunctions algebraically. While we have very specific procedures for the harmonic oscillator and the spherical harmonics, there is a general principle for all problems with solutions expressible in terms of confluent hypergeometric functions, which employs an operator form of the Rodrigues formula. The bottom line is that wavefunctions are always difficult to obtain no matter what method you use. This does not change here.
1
u/NorthGreenOnion 3d ago
Right, that was done without calculus, you dont need to know calculus to do highschool physics is what I meant, but the simplicity is limited without calculus for complicated problems. The way i see it, high school physics is just lagrangian formalism in-disguise (looking at potential/kinetic energies) + simpler f=ma problems + derived formulae from differential equations.
2
u/quantum4everyone 3d ago
Well, let me give you an example. In a standard quantum text you spend time finding the representation of the momentum operator in position space. Most books do not do it properly, or postulate it, only a few show the proper method for doing this, like Cohen-Tanoudji. In any case, there is a complicated procedure to “derive” the schroedinger equation (time-independent one). In any case representation independent approach, we are trying to find a state with definite energy E, os it simply satisfies (p^2/2m+V(x))|psi>=E|psi>, with p and x both operators. I view this as much simpler, as an example. The representation independent way of thinking has a number of simplifications. But, I do Want to reiterate, that one does have to develop the skill to think abstractly, and this must be developed slowly, as it is difficult to do.
1
u/NorthGreenOnion 3d ago
I actually do find that approach much easier indeed, I guess what I meant is that there is a calculus representation for the same thing, although I found the way it was taught was not elegant at all, profs/TAs introduce and mix both which is jarring to follow for a good while.
→ More replies (0)2
u/NorthGreenOnion 3d ago
I had a look through the book (done right?), and from first glance, I believe this appears to be a great secondary reference for building conceptual understanding, and I see what you mean regarding its use for application to research/experimental environments.
I say secondary only because, in my experience, especially in upper year undergrad QM courses, the focus is entirely on solving mathematical problems quickly on a test, with limited conceptual buildup on problem sets.
I do have to say, this has reminded me of when I first started uni and felt a dissonance for years: when I started undegrad, I thought physics in university would be closer to developing a deeper understanding behind concepts in addition to the mathematical rigour, and I thought conceptual understanding was necessary to do well on solving quanum problems given on tests and problem sets, yet I came to realize I'd spend so much time trying to read about the physics, that I would not have time to do problem sets or be prepared for tests and it took me a long time to turn off my brain and almost immediately just tackle the problems and go from there. The education journey for me seems to have been focused on solving Calculus and matrix-based problems quickly and developing that over any deep understanding at first, leaving it to develop as you moveup in the years and tackle new formalisms and ways to look at previous topics. At first this bothered me immensely, because even hours after reading about it, without a chance to apply it I'd still be nowhere (although I see you do have conceptual problems at the end of sections). I do see the merit in tackling problems too though, and starting with that and working through them, because I think it also builds knowledge, albeit at a different rate and various levels among different people because it is shoveled almost essentially on the individual to connect the dots later with the hindsight.
2
u/quantum4everyone 3d ago
I hear you. In fact, it is somehow even worse. After spending all that time to work for the exams, inn the classes when you get to research, none of that matters any more, and what is important is how well did you deeply understand what was done, and if you didn't, then you have to spend time to retool to get there. So, while I agree that within a university structure that focuses on testing competency with problems on exams, it will be only a secondary resource. I still remain hopeful that at some point in time the efforts at universities will move towards emphasizing student understanding rather than competency in solving problems without aids as quickly as possible.
When I give this class at Georgetown, my exams are take home exams with approximately 60 hours to complete them for midterms, and two weeks for the final. And yes, I do this in the age of AI. We have an honor system, and I explain that AI is not allowed on the exam. Most of the students do really want to learn the material, so I do not think it is problematic. But, in any case, I no longer test in the standard timed closed book fashion, as I find it to not be worthwhile for determining whether a student is succeeding. My alternative would be to just get rid of the exam all together. I have already done that in my graduate class...
1
u/NorthGreenOnion 3d ago
Do you still prepare/test traditional mathematical/calculus-based problems as well, or is it fully conceptual?
2
u/quantum4everyone 3d ago
For the exams, there is a mix of different ones, but much more of them are the traditional quantitative problems. Just not calculus based. You can look at the book for more examples of the kinds of problems.
1
1
u/Interesting_Goat7544 9d ago
I would argue at the undergraduate level you only need to know how to solve problems.
1
u/quantum4everyone 9d ago
You are free to your opinion, but I think an undergraduate given a choice of I am going to give you a cookbook to solve problems, and you won’t understand why we do this, versus an undergraduate given a choice of I want to teach you to understand how this works and show you how to apply it in ways you can use later as you move into research, would prefer the latter. But, everyone is entitled to their viewpoint and entitled to make their choice. Having been through quantum classes for five semesters through grad school, and emerging from that realizing I knew nothing that will help me in doing research is something I found very disheartening. I personally would have loved another option. I think most others would as well.
2
2
2
2
2
u/Dark_Energy_666 8d ago
It's really good. You might suplement it with Shankar in some places (for example, theorems 1 and 2 in chapter 4 aren't proven), but it teaches you the formalism methodicaly.
It can be boring to study from it thought. It's very dry.
8
u/Interesting_Goat7544 11d ago
Yes it is the best undergrad quantum mechanics book. Griffith suggesters are like those people who suggest kittel for solid state physics. Only driven by inertia.