1. ### I What part of physics describes what happens just outside of an electron?

Coulomb's law for three dimensional space is an empirical law that describes the forces between two stationary point charges and is defined as: \vec{F}=\frac{K q_1 q_2 (\vec{r}_1-\vec{r}_2)}{|\vec{r}_1-\vec{r}_2|^3} From Coulomb's law, the magnitude and direction of an electric field produced by...
2. ### B Does the Higgs Boson really have 0 spin?

Does the Higgs Boson really have 0 spin or is the spin between 0 and 1/2 x (1.054 571 817... x 10-34 J s)?
3. ### A Green's function for tunneling electrons between quantum dots

Good afternoon! I am writing with such a problem, I hope to find someone who could help me. I'm almost desperate! So, there is such a thing as the Braess paradox, this is a classic paradox for roads and power grids, and there is also such an article...
4. ### I How to work in the |F,m_F> states in hyperfine structure

Suppose that we have two atoms with one proton one electron each, and these electrons interact with each other. The states for the electrons are the singlet(S=0) and the triplet states(S=1). My question is if i have to keep the nuclear spin of the protons parallel when i write the states, for...
5. ### A Eigenvalues of Hyperfine Hamiltonian

I was reading a paper on Radical-Pair mechanism (2 atoms with 1 valence electron each) and the author used the hyperfine hamiltonian $$H_{B}=-B(s_{D_z}+s_{A_z})+As_{D_x}I_x+As_{D_y}I_y+as_{D_z}I_z$$ and found the following eigenvalues: a/4 (doubly degenerate) , a/4±B , (-a-2B±2√(A^2+B^2)) ...
6. ### I Solving Schrödinger's equation for a hydrogen atom with Euler's method

Hi, first-time poster here I'm a student at HS-level in DK, who has decided to write my annual large scale assignment on Schrödinger's equation. My teacher has only given us a brief introduction to the equation and has tasked us to solve it numerically with Euler's method for the hydrogen atom...
7. ### A Entanglement Witnesses close to GHZ states

Consider page 2 of Toth's paper Entanglement detection in the stabilizer formalism (2005) . To detect entanglement close to GHZ states, they construct entanglement witnesses of the form $$\mathcal{W} := c_0 I - \tilde{S}_{k}^{(GHZ_N)} - \tilde{S}_{l}^{(GHZ_N)},$$ where...
8. ### Help with the matrix representation of <-|+|->. Does "+"=|+>?

Trying to use <+|+>=1=<-|-> and <-|+>=0 to prove each iteration of the equation, so I have 6 different versions to prove. But the part I'm currently stuck on is understanding how to simplify any given version. I've written out [S_x,S_y]=S_xS_y\psi-S_yS_x\psi and expanded it in terms of the...
9. ### A Everettian FAPP solipsism

Travis Norsen in his paper Quantum Solipsism and Non-Locality seems to believe that Everettian QM implies some sort of solipsism. He falls it FAPP (for all present purposes) solipsism. (I must say that as a geologist this goes over my head a bit!) However I have recently read Sean Carrolls...
10. ### I Consistent Histories Interpretation - History

I have just finished reading the book 'Three Roads to Quantum Gravity' by Lee Smolin. My question interestingly is associated with my geology background. Lee Smolin notes Fay Dowker concludes that if Consistent Histories is true then we cannot deduce the existence of dinosaurs 100 million...

21. ### I Clebsch–Gordan coefficients: An Identity

Hi, everyone. I'm trying to get the next identity It is in the format <j1, j2; m1, m2 |j, m>. I hope you can help me
22. ### Bohr-Sommerfeld, WKB, and current-biased Josephson junction

I've already found the turning points, in the case of the left turning point, the local minimum of the potential, ##\delta_{min}=1.11977## when evaluating for an arbitrary value of current ##J=0.9I_C##. The left turning point is therefore ##\delta_r=2.48243##. I know the Bohr-Sommerfeld...
23. ### Finding energy eigenvalues with perturbation

I know the basis I should use is |m_1,m_2> and that each m can be 1,0,-1 but how do I get the eigenvalues from this?
24. ### S-wave phase shift for quantum mechanical scattering

a.) The potential is a delta function, so ##V \left( r \right) = \frac {\hbar^2} {2\mu} \gamma \delta \left(r-a \right)##, therefore ##V \left( r \right) = \frac {\hbar^2} {2\mu} \gamma ## at ##r=a##, and ##V \left( r \right) = 0## otherwise. I've tried a few different approaches: 1.) In...
25. ### Computing the wave function of a square potential

The book's procedure for the "shooting method" The point of this program is to compute a wave function and to try and home in on the ground eigenvalue energy, which i should expect pi^2 / 8 = 1.2337.... This is my program (written in python) import matplotlib.pyplot as plt import numpy as...
26. ### Qubit Operations

Part a: Gate H X Y Z S T R_x R_y Theta pi pi pi pi pi/2 pi/4 pi/2 pi/2 n_alpha (1/sqrt(2))*(1,0,1) (1,0,0) (0,1,0) (0,0,1) (0,0,1) (0,0,1) (1,0,0) (0,1,0) Using the info from the table and equation 1, I find: U_H=(i/sqrt(2))*[1,1;1,-1] U_X=i*[0,1;1,0] U_Y=i*[0,-i;i,0] U_Z=i*[1,0;0,-1]...
27. ### Perturbation treatment of hydrogen molecular ion

hi guys i am a the third year undergrad student and in this 2nd semester in my collage we should start taking quantum mechanics along with molecular physics , our molecular physics professor choose a book that we are going to take which is " molecular physics by wolfgang Demtroder " when i...
28. ### Plotting the radial wave function of Deuteron in a finite well

To plot ##u(r)## we need to find the solutions for each region. Which is in the relevant equations part. Now, I have to do this numerically. Using python 3.7 I made an ##u## which is filled with zeros and a for loop with if/elseif statement, basically telling it to plot values for whenever...
29. ### I What exactly is a measurement device and how does it work?

What exactly is a measurement device and how does it carry out a measurement? For instance, in the double slit experiment, you always hear about particle/wave duality. When it's not being measured it behaves like a wave but when a measuring device is placed by the slits, it behaves like a...
30. ### Five State Quantum System, need help understanding the question

I’ve never worked with a quantum system with more that two states 1, -1, and I’ve just gotten this homework problem. I'm not sure what it means. Does this mean it has five states? Why are there two 0’s and two 1’s?