Abstract
We have to go through a few more formalities before we can resume our discussion of quantum effects in physics. In particular, we need to address minimal uncertainties of observables in quantum mechanics, and we have to discuss transformation and solution properties of differential operators.
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Notes
- 1.
W. Heisenberg, Z. Phys. 43, 172 (1927).
- 2.
Frequency-time Fourier transformation for Green’s functions and potentials, which generically will depend on two arguments, will often appear asymmetric due to translation invariance \(G(t,t') = G(t - t') \leftrightarrow G(\omega,\omega ') = G(\omega )\delta (\omega -\omega ')\):
$$\displaystyle{ G(t) = \frac{1} {2\pi }\int \!d\omega \,G(\omega )\exp \!\left (-\mathrm{i}\omega t\right ),\quad G(\omega ) =\int \! dt\,G(t)\exp \!\left (\mathrm{i}\omega t\right ). }$$(5.11) - 3.
Free states with initial conditions \(\langle \boldsymbol{x}\vert \psi \rangle \equiv \langle \boldsymbol{ x}\vert \psi (t = 0)\rangle\) yield frequency representations \(\langle \boldsymbol{x}\vert \psi (\omega )\rangle\) in terms of convolutions of \(\langle \boldsymbol{x}\vert \psi \rangle\) with Bessel functions. This is explained in Appendix J, especially equations (J.32)and (J.34–J.36). However, if you began only recently to learn quantum mechanics, don’t let yourself become distracted by the technicalities of Appendix J. Save it for later.
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Dick, R. (2016). Formal Developments. In: Advanced Quantum Mechanics. Graduate Texts in Physics. Springer, Cham. https://doi.org/10.1007/978-3-319-25675-7_5
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DOI: https://doi.org/10.1007/978-3-319-25675-7_5
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