Quantum phyics Definition and 60 Threads

Can any expert help me in explaining how this example below get the reduced density matrix from the density matrix in bipartite system. $$\rho =\frac{1}{4}\begin{pmatrix} 1 & 1 & cos(\frac{\alpha}{2})-sin(\frac{\alpha}{2}) & cos(\frac{\alpha}{2})+sin(\frac{\alpha}{2}) \\ 1 & 1 &...

Can anyone suggest me a book on quantum electrodynamics for beginners? Thanks in advance

Homework Statement A beam of electrons with kinetic energy 50 eV is fired at a 100 nm thick crystalline nickel foil. (a) Calculate the speed of the electrons in the beam.(b) Based on your answer to part (a), state, with justification, whether classical (Newtonian) mechanics correctly...

Just a thought: The momentum quantum number given for s states is l = 0. If an S state electron dropped in energy, and emitted a photon with l = 1, what would take place? Am I correct that the electron could only drop to a lower l = 0 (an S state) orbital?

1. Homework Statement Given the following diagram of a finite potential well, calculate the rate at which the right-going wave is bringing probability density up to the barrier. (Ignore interference with the left-going wave. ) (Hint: you can get the velocity from the energy, and the average...

So I really have a few questions. First, is it wise to take the following classes in the same semester? Quantum Mechanics I - At the level of Griffiths' Intro to Quantum Mechanics, chapters 1-5ish Classical Dynamics - At the level of Thorton and Marion, Chapters 1-12, ends with coupled...

hello all Prior to my studies in QM I would need a brief intro to quantum physics. I know there are lot of books on modern physics that cover these topics, but really like Griffiths' style, and my QM textbook is precisely his QM book. So, my question is if "revolutions in 20th century physics"...

Hi. 4 years ago my child asked to me a question... What will be happen, if the light is stop? I tried to answer it ... But my knowledge is insufficient. (I had been educated at social science, specially labor laws) . So I searched, tried to learn something new... So I liked physics. Of course it...

I'm just starting this, but what would the complex conjugate of Ψ(x,t) in the equation : |Ψ(x,t)|^2= Ψ(x,t)* Ψ(x,t) be.. Let's just say, for example, that x is 4 and t is 9... Please help if you can.. Could you please help me out with the steps to completing this, because I really want to...

Do I get this correctly: if a wave/particle is not measured, it is in the wave state, and if it is measured, it becomes a particle, fixated on an eigenstate of the probability distribution of the wave function. So the universe - matter, light, each natural phenomenon - if unmeasured, is in a...