# Questions tagged [quantum-spin]

Fundamental characteristic property of particles which together with orbital angular momentum acts as the generator of rotations and which doesn't have a classical equivalent but is sometimes compared to and contrasted with classical intrinsic angular momentum.

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### Complex rabi frequency

I am learning quantum optics. In the book written by Scully includes complex rabi frequency, when dealing with $\Delta$ level configuration, the Hamiltonian including laser-atom interacting concludes ...
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### Which book (or article) has detailed calculation for Quantum Heisenberg Model for three or four spins?

A I need to write a program to calculate Quantum Heisenberg Model for any number of spins (with or without external magnetic field). Each spin is spin 1/2. I know how to do this calculation for two ...
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### What is the value of the inner product $_x\langle+|-\rangle$?

I know that $\left|_x\langle+|-\rangle\right|^2 = 1/2$, so is it just as simple as taking the square root of $1/2$? Thanks.
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### Why is it that the Callan-Gross relation predicts that quark has spin 1/2?

I'm studying deep inelastic scattering, and currently at the part where they say the Callan-Gross relation: $$F_1 (x) = \frac{1}{2x} F_x (x)$$ where $F_1$ and $F_2$ are the dimensionless structure ...
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### What is the 4-spin vector of a photon?

The photon, being a vector boson has 2 spin states, $\pm 1$. In relativity, we can determine the four-spin vector $s^{\mu}$ of a particle (see e.g. Costa et al. 2017). What would $s^{\mu}$ be for a ...
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### Stern-Gerlach experiment interpretation [on hold]

It seems to me there is a problem with the usual interpretation of the Stern-Gerlach experiment. Sending a magnetic dipole on a path through a magnetic field would, on classical assumptions, affect ...
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### Direct measurement of $\mathbf S^2$

For concreteness, consider two spin-1/2 particles with spin vectors $\mathbf S_i=(S_i^x,S_i^y, S_i^z)$. The total Hilbertspace is four-dimensional, and as a basis we can take the (simultaneous) ...
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### Does electron affinity decrease with charging?

Lets consider two materials A having higher electron affinity than B while both are not too far off. If they are both insulators and A accumulate charges due to triboelectric effect. Than after a ...
To my understanding, decomposing the tensor product of two particles with spins $s_1$ and $s_2$ works as follows: $$\mathcal{H_{s_1}}\otimes \mathcal{H_{s_2}}=\mathcal{H_{s_1+s_2}}\oplus\mathcal{H_{... 1answer 65 views ### Constructing singlet state in second quantization formalism I am trying to understand the second quantization formalism. Let's say we have a system of fermions (e.g. electrons) with spin in an array of quantum dots. The creation and annihilation operators c^{\... 0answers 71 views ### Is the magnetic dipole of the electron an intrinsic property? The profound answer to the question How permanent magnets work? starts with Sub-atomic particles such as electrons, protons, and neutrons (and many others) have a fundamental quantity called a spin ... 2answers 155 views ### Photon carries spin angular momentum of \hbar I know from numerous articles and also wiki (http://en.wikipedia.org/wiki/Spin_angular_momentum_of_light) that a photon carries spin angular momentum of \hbar. How to prove it mathematically? What ... 1answer 135 views ### Why does a spinning nucleon generate a magnetic field? I am trying to understand how NMR works, but I am not sure why a spinning nucleon produces a magnetic field. Is this a consequence of the quark structure inside? 2answers 88 views ### Why do we use this diagram/model for elementary particles? The model of elementary particles is analagous to the periodic table, which is organized not only beautifully, but also functionally. The typical model for the elementary particles that pops up ... 0answers 28 views ### Using entangled qubits to communicate [duplicate] After reading up on quantum mechanics considering entangled qubits I was asking myself this simple question: If one qubit (A) positioned on earth is entangled with another qubit (B) which is - say - ... 0answers 74 views ### Are there compelling reasons not to organize the elementary particles by charge and spin? [closed] I don't like the way the standard model is currently displayed (see second picture for reference). It does a poor job of abstracting the information into something understandable. As far as I ... 1answer 864 views ### Did the Feynman heuristic of “simple effects have simple causes” fail for spin statistics? Someone here recently noted that "The spin-statistics thing isn't a problem, it is a theorem (a demonstrably valid proposition), and it shouldn't be addressed, it should be understood and celebrated." ... 0answers 15 views ### Factorizing spin part and space of many electron wave function of an atom's ground state I am trying to write the ground state wave function of a 10 electron atom as a product of space part and anti-symmetric spin part.$$1s\uparrow,1s\downarrow2s\uparrow, 2s\downarrow2p_{x}\...
I'm trying to find the expectation value of the spin in the $y$ direction after applying a $\pi/2$-$\pi/2$ sequence of pulses. In Slichter's Principles of Magnetic Resonance, he does a $\pi/2$-$\pi$ ...