Tagged Questions

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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Can hydrogen atom state be a superposition of 2 pure states with opposite spin?

The task is: We are performing measurements on hydrogen atom, that is in an unknown state $\psi$. $\psi$ is a superposition of $n=1$ and $n=2$ pure states and is orthogonal to ...
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Does point group symmetry also act within “spin space” for a lattice spin system?

As an example, let's consider a quantum spin system on a 2D square lattice. The lattice point group symmetries include $C_4$ rotation, parities, etc.... And let's take $C_2$ symmetry (2-fold rotation) ...
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Are these two spin states the same?

Consider two sets of axes, $xyz$ and $x'y'z'$, and the two spin states \begin{align} |\psi\rangle &= A(|+_x\rangle + |+_y\rangle + |+_z\rangle)\\ |\psi'\rangle &= A(|+_{x'}\rangle + ...
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Why do particles have spins such as $1/2$, $3/2$, $5/2$? [duplicate]

What does it mean to have 'half' spin? I have looked on Wikipedia and a few youtube videos on spin but they don't explain what it means to have $1/2$ spin. I am 18 and only starting to learning about ...
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How can we measure chirality in experiments?

Chirality is a concept quite different from helicity. These two concepts only happen to have the same numerical value for massless particles. I understand that we can measure helicity, but how can we ...
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How does De Broglie–Bohm theory or pilot wave theory explain the results of the Stern–Gerlach experiment?

The Copehagen interpretation of QM explains the Stern–Gerlach experiment by asserting that a particle is in a superposition of states and doesn't have a definite spin until measured. However, the de ...
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Why does the Stern–Gerlach quantum spin experiment conflict with classical mechanics?

My understanding of the Stern–Gerlach experiment is that neutral (0 total charge) particles are sent through a non-homogeneous magnetic field, with the expectation that the field will push that ...
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Azimuthal angle in bloch sphere

I was wondering if there is any direct physical meaning behind the Bloch sphere parametrization in the sense that if I choose the angle $\phi =0$, then what does this mean for my spin state? Does ...
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Goldstone modes of spin density wave

A spin density wave (SDW) is a phase in which a material suddenly shows a periodically modulated spin density $S_{\vec{q}}(\vec{r})$ below a certain critical tempereature $T_C$. Obviously some kind ...
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Question about surface term in QFT problem

I am trying to follow the solution of the following problem (Srednicki 39.2): To show that: $$J_z b_s^\dagger(p\hat z)|0\rangle=\frac{1}{2}\ s\ b_s^\dagger(p\hat z)\ |0\rangle,$$ where $J_z$ ...
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Numerical study of Hubbard Model and Spin Charge Separation effect

Hi, How can i implement the creation operator effect on the ground state(in FORTRAN)? we calculate the ground state using modified Lanczos method,and we obtain a vector(array) with lots of numbers ...
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Is it proper to describe electron spin as being similar to light polarity?

We always hear that electron spin is merely analagous to angular momentum in classical mechanics, but it never seems to be followed up by what is actually going on based on first principles (not even ...
In my textbook the coherence of a spin state $|\psi\rangle$ is measured by the quantity $|\langle \uparrow|\psi| \downarrow \rangle|$. The thing is that I am not sure how this quantity is related to ...