Questions tagged [semiclassical]
Semiclassical descriptions involve a base/background part described classically, and quantum parts representing an effective development in powers of Planck's constant, ħ. They cover systematic approximations such as the WKB, intuitive approaches to the correspondence limit, and a broad class of interstitial physical phenomena.
385 questions
7 votes
4 answers
833 views
How can one see the disappearance of entanglement as one transitions from a quantum to a classical system?
I am trying to combine two concepts in this question: quantum entanglement and the deformation quantization. From the definition of entanglement on Wikipedia: Consider two arbitrary quantum systems $A$...
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2 votes
0 answers
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Centrifugal term in cylindrical coordinates
When solving an equation of motion with spherical symmetry using the WKB approximation, one usually encounters a centrifugal term that diverges as $$ \sim \frac{l(l+1)}{r^2}. $$ What is the ...
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-4 votes
1 answer
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Does the semiclassical path integral formulation of quantum tunnelling admit a non-linear (curved) extremal path in imaginary time? [closed]
In the semiclassical (WKB / path-integral) description of quantum tunnelling, the dominant contribution to the transmission amplitude comes from the extremum of the Euclidean action $$ S_E = \int \...
4 votes
0 answers
153 views
WKB at second order
I have a similar question to this forum that was asked 6 years ago... Transmission coefficient of second-order WKB approximation I am working on solving a differential equation using the WKB method up ...
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1 vote
0 answers
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Treatment of the WKB method in "An Introduction to Quantum Mechanics", 3rd edition by David J. Griffiths and Darrell F. Schroeter
In the third edition of the book "An Introduction to Quantum Mechanics" by David J. Griffiths and Darrell F. Schroeter the so called Wentzel-Kramers-Brillouin (WKB) method is treated in ...
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1 vote
0 answers
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Solving the Schrodinger equation in the single excitation manifold
I have been trying to solve the Schrodinger equation for a TLS weakly coupled to the EM field along with a 'semi-classical' atom-drive term, with the TLS initially in ground and the field initially in ...
2 votes
1 answer
263 views
Semiclassical electron dynamics and Pauli exclusion principle
I believe a similar question is asked here, but there doesn't seem to be a satisfactory answer so I'd like to reformulate it. In the semiclassical model of electron transport, electrons are described ...
7 votes
1 answer
687 views
Landau&Lifshitz's comment on WKB formula
In L&L's quantum mechanics textbook $\S 46$, they derived the WKB approximated wave function at the classically forbidden region: $$ \psi = \frac{C_1}{\sqrt{|p|}} \exp\left(-\frac{1}{\hbar} \int |...
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1 vote
1 answer
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What does Weinberg mean by “integrating out the auxiliary field $h$” in the BRST formalism for QED?
In The Quantum Theory of Fields, Volume II, Weinberg defines the BRST variation $\delta_\theta$ as follows: \begin{align} \delta_\theta \psi & = i t_\alpha \theta \omega_\alpha \psi \tag{15.7.7} \\...
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0 votes
1 answer
155 views
Wavefunctions have constant phase velocity? Schrödinger assumes this for deriving his equation
I was reading Schrödinger's paper, in which he first introduces his wavefunctions and equations. Before explaining the problem I encountered, I will try to set the stage by mentioning what he ...
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4 votes
0 answers
129 views
AdS/CFT correspondence -- semi-classical bulk for CFT states
How to construct a semi-classical bulk dual for a given CFT state in the context of AdS/CFT correspondence? In particular, I am looking for an explanation/proof of the statement in https://arxiv.org/...
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6 votes
4 answers
397 views
Construction of a semi-classical field theory
I am reviewing some basic aspects of the passage from classical field theory to quantum field theory. The steps to obtain a quantum theory are (I). Find a suitable classical action $S$ whose ...
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2 votes
3 answers
536 views
Veritasium video, where does the phase formula in the Feynman integral come from?
In this Veritasium video "Infinite Slit Paradox: Something Strange Happens When You Trust QM", the Feynman integral is built up from just one formula (that is completely brushed under the ...
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2 votes
1 answer
218 views
What is the "classical orbit" referenced in the Correspondence Principle?
I seem to be missing a key concept in understanding Bohr's correspondence principle as applied to electron transitions in atoms. In this article, they break the principle into three parts, which they ...
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1 vote
2 answers
303 views
How did Niels Bohr derive the quantization of angular momentum from the correspondence principle?
I use the information from the text titled The Bohr Atom written by Michael Fowler and the Wikipedia page titled Larmor formula while framing my question. In the section titled "The ...
