- List of Backups
- View the diff current.
- View the source.
- View the backup.
- Go to Thomas-September Progress (Open).
- 1 (2013-09-02 (Mon) 12:23:37)
- 2 (2013-09-02 (Mon) 12:28:01)
- 3 (2013-09-02 (Mon) 18:30:43)
- 4 (2013-09-02 (Mon) 20:42:57)
- 5 (2013-09-03 (Tue) 18:06:54)
*6 (2013-09-03 (Tue) 22:03:06)*- 7 (2013-09-04 (Wed) 12:48:15)
- 8 (2013-09-04 (Wed) 16:23:39)
- 9 (2013-09-04 (Wed) 22:33:52)
- 10 (2013-09-05 (Thu) 12:25:31)
- 11 (2013-09-05 (Thu) 16:08:56)

- The added line is THIS COLOR.
- The deleted line is THIS COLOR.

[[Saito Group (Open)]] Started by Thomas.2013.09.02 This is Thomas's logbook for September of 2013. #contents * 1st week [Electron-Photon Interactions] [#te145562] -09.02 --The Hamiltonian for the electron-photon interaction is given by $H = \frac{1}{2m} \left(\mathbf{p}-\frac{q}{c}\mathbf{A}\right)\left(\mathbf{p}-\frac{q}{c}\mathbf{A}\right) +q\phi$, in this equation $\mathbf{p}$ is the linear momentum, $q$ is the charge of the particle, $\mathbf{A}$ is the vector potential, $m$ is the particle's mass, $c$ is the speed of light and $\phi$ is the scalar potential. It is possible to check this by using the canonical equations from Hamilton, $\dot{\mathbf{r}}=\frac{\partial H}{\partial \mathbf{p}}$ and $\dot{\mathbf{p}}=-\nabla H$. --From those last equations together with the following identities $ \frac{d \mathbf{A}}{d t} = \frac{\partial \mathbf{A}}{\partial t} + \left(\frac{d \mathbf{r}}{d t} \cdot \nabla \right)\mathbf{A}=\frac{\partial \mathbf{A}}{\partial t} + (\mathbf{v} \cdot \nabla)\mathbf{A}$ and $(\mathbf{v} \cdot \nabla) \mathbf{A} = -\mathbf{v} \times (\nabla \times \mathbf{A}) + \nabla(\mathbf{v}\cdot \mathbf{A})$ With all this considered it was possible to arrive at the equation of motion of a particle under an electromagnetic field, $m \ddot{\mathbf{r}}=\frac{q}{c}(\mathbf{v} \times \mathbf{B}) + q \mathbf{E}$. --Next steps: ---Consider the wave functions from quantum well, hydrogen atom, and solve with the electromagnetic(electron-photon interaction) perturbation. -09.03 --By looking at the previous Hamiltonian in a different shape, $\mathcal{H}=\left[\frac{p^2}{2m} + V(\mathbf{r})\right] -\frac{q}{cm} \mathbf{p} \cdot \mathbf{A} + \frac{q^2}{c^2} \frac{\mathbf{A}^2}{2m}$ where the term inside the brackets is actually the unperturbed hamiltonian, and the other terms are the perturbations that arise from the electomagnetic field influence. --As the electromagnetic field is just a perturbation, it is not so strong, therefore it is possible to disregard $\mathbf{A}^2$, and consider the perturbation Hamiltonian as $\mathcal{H}_{\mbox{eR}}=-\frac{q}{cm} \mathbf{p} \cdot \mathbf{A}$. --Taking a monochromatic wave over a quantum well of length $R$ it is possible to find the new wavefunction after taking the $\left< \phi |A|\phi \right>$. --Next Steps: ---Find the actual new wavefunctions.