Questions tagged [quantum-mechanics]
Quantum mechanics describes the microscopic properties of nature in a regime where classical mechanics no longer applies. It explains phenomena such as the wave-particle duality, quantization of energy, and the uncertainty principle and is generally used in single-body systems. Use the quantum-field-theory tag for the theory of many-body quantum-mechanical systems.
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Do all operators which fulfil mathematical conditions in Quantum Mechanics correspond to an observable? [duplicate]
In my understanding of Quantum mechanics, which is demonstrably limited, Operators have corresponding observables. I imagine it like operators helping draw a graph, with probability on the y-axis and ...
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Are there alternatives to the collapse of the wave function? [closed]
The equations of classical physics are time reversible -- unchanged when $t$ is replaced by $-t$. The Schrodinger equation in quantum mechanics is time reversible -- unchanged when $t$ is replaced by ...
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Does spectroscopy count as a measurement of electron spin?
There was some debate in my modern physics course about the statement
"The spin of an electron can only be measured in the presence of an external magnetic field".
So far in the course, ...
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Variational Principle for the $\rm H_2^+$ ion
I am following the book "Introduction to the Quantum Theory" by David Park, and I've run into a problem. The text calculates the ground state potential energy of the $\rm H_2^+$ ion using ...
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The density operator as a function of the Hamiltonian in equilibrium
I am studying statistical mechanics on my own with several books (Pathria, Huang, Reichl, etc..) and there is a conclusion which is stated in all these books is but never showed. This might be so ...
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Can the mass of a proton be used as a surrogate for the strength of gluon color charge? [closed]
If a proton has mass 938 MeV/c^2, and gluon energy makes up 99% of the mass of the proton, can we say that gluon color charge has a strength of .99 x 938 = 928 MeV in equivalent units, recognizing ...
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Quantum Entanglement Field Theory by Ammar Hafeez [closed]
Is it possible for entanglement to be a dynamic field, suggesting that particles become entangled through their interaction with this field, as opposed to viewing entanglement as a direct, passive ...
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Visualise Hadamard gate as addition of $x$ and $z$ gate
I try to imagine the Hadamard gate on a Bloch sphere and it is obvious that it is the sum of the Pauli $x$ and $z$ gate matrices.
So that means we rotate the "vector" around the x axis and ...
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Path integral in quantum mechanics and expectation values [closed]
How to calculate any expectation value from path integral in quantum mechanics? In QM path integral the initial and final points are fixed and points between them are varied. But as far as i ...
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Time-domain algorithm to generate noise with Power Spectral Density (PSD) $S(\omega,T) \propto \coth(\omega/T)$ sequentially [closed]
I need to numerically generate colored noise with a Power Spectral Density (PSD) $S(\omega,T) \propto \coth(\omega/T)$ (quantum thermal noise). I cannot use standard Spectral Synthesis (Inverse FFT) ...
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Is there a connection between Ehrenfest equation and von Neumann equation? [closed]
I understand how Ehrenfest is sort of giving a correspondence between classical and quantum whereas von Neumann is more like a quantum mechanical equivalent of Liouvilles equation. But do they share ...
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Are the involutions defining spin in the 3D Clifford algebra the vectors or the bivectors?
We can embed the spinors of a Clifford algebra into the Clifford algebra itself by representing them as a minimal left ideal. I'm looking at the case of 3D space where a chosen basis satisfies $e_1^2=...
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Why the Expectation Value of a unnormalised state $|\psi\rangle$ is $\langle A\rangle_\psi=\frac{\langle\psi|A|\psi\rangle}{\langle\psi|\psi\rangle}$? [closed]
The typical expectation value formula given most places is
$$\langle A \rangle_\psi = \langle\psi|A|\psi\rangle.$$
this assumes that the state is normalised.
For unnormalised states the formula is
$$\...
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How to calculate transition dipole moment computationally? [closed]
Interested to calculate TDM of a molecule in the presence of a dielectric. What is the go-to way right now in research circles?
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Is quantum channels can be simulated via quantum trajectories? [closed]
Lookin for a way to run quantum circuits with de-polarizing noise via quantum trajectories and not density matrix
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