User HerpDerpington - Physics Stack Exchange

11 votes

2 answers

6k views

Are the creation and annihilation operators time-dependent?

asked Jul 6, 2018 at 16:41

7 votes

2 answers

3k views

Orthogonality of Bloch factors in $k$

asked Feb 7, 2020 at 19:59

6 votes

2 answers

2k views

Deriving the Boltzmann distribution using the information entropy

asked Mar 2, 2018 at 14:08

5 votes

1 answer

4k views

Why does the factor $\sqrt{-g}$ make the volume element invariant?

asked Jun 16, 2019 at 17:42

4 votes

1 answer

302 views

How does "coherence" contribute to inverting a two-level system?

asked Jul 18, 2018 at 21:18

4 votes

1 answer

426 views

What are zero-energy Rindler photons?

asked Jun 21, 2019 at 15:59

4 votes

2 answers

907 views

Time evolution of the operators vs. the expectation values

asked Jul 9, 2020 at 14:18

4 votes

2 answers

230 views

Evaluating the integral of the total energy of the EM field in a nonlinear dielectric

asked Aug 5, 2024 at 18:03

4 votes

0 answers

132 views

Typo in "The Quantum Theory of Optical Coherence"?

asked Aug 19, 2025 at 9:44

3 votes

1 answer

289 views

How to normalize the states in the continuous limit?

asked May 22, 2023 at 20:46

3 votes

2 answers

879 views

Intuition behind the $k$-indexing of wavefunctions

asked Jan 13, 2020 at 0:10

3 votes

1 answer

1k views

Confusion about the Euler equation: $U = TS - pV + \sum_{i = 2}^M x_iy_i$

asked Mar 4, 2018 at 15:17

3 votes

1 answer

2k views

Fourier transforming between time space and wavelength space

asked May 9, 2017 at 16:33

3 votes

1 answer

1k views

In which direction does the positron's magnetic moment point?

asked Dec 3, 2018 at 17:57

2 votes

1 answer

1k views

Why does the 2D hexagonal lattice have a different tight binding band structure than Graphene?

asked Nov 9, 2018 at 16:22

2 votes

1 answer

190 views

Why to we take the Minkowski vacuum to calculate the thermal Unruh distribution?

asked Jun 20, 2019 at 20:34

2 votes

2 answers

137 views

Snell's law for the $D$ field

asked Aug 2, 2024 at 13:55

2 votes

1 answer

248 views

Fourier Optics of lenses and free space translations in terms of wave vectors

asked Dec 12, 2024 at 16:08

1 vote

1 answer

142 views

What is the intuition behind $\vec{D}$ and $\vec{E}$ not being parallel for the extraordinary beam?

asked Aug 3, 2024 at 22:02

1 vote

1 answer

140 views

Quantizing the EM field: "The $\boldsymbol{k}_{\perp},k_z,\omega$ approach"

asked Mar 13, 2021 at 20:33

1 vote

0 answers

211 views

The effective (time integrated) Hamiltonian in the Heisenberg picture

asked Mar 15, 2021 at 17:34

1 vote

1 answer

90 views

Where is the error in my calculation for a simple bosonic system?

asked Apr 21, 2021 at 15:33

1 vote

1 answer

185 views

How do I correctly evaluate this simple expression with delta-commutator operators?

asked Feb 10, 2022 at 0:31

1 vote

0 answers

226 views

Where did the the $\delta(0)$ go? [closed]

asked May 20, 2023 at 19:47

1 vote

1 answer

257 views

Swapping expectation value of derived operator with derivative of expectation value

asked Jul 7, 2020 at 12:47

1 vote

0 answers

59 views

References for listings of point group operations

asked Apr 18, 2020 at 13:07

1 vote

1 answer

83 views

What causes this high frequency "noise" in HHG spectra?

asked Jan 30, 2020 at 17:43

1 vote

0 answers

153 views

Are Bremsstrahlung and the Unruh effect equivalent?

asked Jun 21, 2019 at 20:27

1 vote

0 answers

69 views

A fast and automated way to check if symmetry (space group) operations preserve a lattice

asked Aug 23, 2019 at 20:58

1 vote

1 answer

474 views

The role of the harmonic oscillator eigenfunctions in quantum optics

asked Jan 12, 2019 at 22:32

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41 Questions

Are the creation and annihilation operators time-dependent?

Orthogonality of Bloch factors in $k$

Deriving the Boltzmann distribution using the information entropy

Why does the factor $\sqrt{-g}$ make the volume element invariant?

How does "coherence" contribute to inverting a two-level system?

What are zero-energy Rindler photons?

Time evolution of the operators vs. the expectation values

Evaluating the integral of the total energy of the EM field in a nonlinear dielectric

Typo in "The Quantum Theory of Optical Coherence"?

How to normalize the states in the continuous limit?

Intuition behind the $k$-indexing of wavefunctions

Confusion about the Euler equation: $U = TS - pV + \sum_{i = 2}^M x_iy_i$

Fourier transforming between time space and wavelength space

In which direction does the positron's magnetic moment point?

Why does the 2D hexagonal lattice have a different tight binding band structure than Graphene?

Why to we take the Minkowski vacuum to calculate the thermal Unruh distribution?

Snell's law for the $D$ field

Fourier Optics of lenses and free space translations in terms of wave vectors

What is the intuition behind $\vec{D}$ and $\vec{E}$ not being parallel for the extraordinary beam?

Quantizing the EM field: "The $\boldsymbol{k}_{\perp},k_z,\omega$ approach"

The effective (time integrated) Hamiltonian in the Heisenberg picture

Where is the error in my calculation for a simple bosonic system?

How do I correctly evaluate this simple expression with delta-commutator operators?

Where did the the $\delta(0)$ go? [closed]

Swapping expectation value of derived operator with derivative of expectation value

References for listings of point group operations

What causes this high frequency "noise" in HHG spectra?

Are Bremsstrahlung and the Unruh effect equivalent?

A fast and automated way to check if symmetry (space group) operations preserve a lattice

The role of the harmonic oscillator eigenfunctions in quantum optics