An applet that illustrates the time dependent behavior of a gaussian wave packet as it encounters a step potential barrier. The parameters are those of an electron moving in GaAs. The user can choose between an infinite step or finite barrier, and can vary the barrier height and width. This item is part of a larger site (http://www.quantum-physics.polytechnique.fr/)containing several related items.
Type of Material:
Java applet.
Technical Requirements:
None
Identify Major Learning Goals:
The user will gain qualitative information regarding the effects of changing the barrier thickness and the "height" of the potential step, on the gaussian wave packet.
Target Student Population:
Introductory to upper-level quantum mechanics.
Prerequisite Knowledge or Skills:
Basic quantum mechanics.
Content Quality
Rating:
Strengths:
Those old enough to remember the venerable "film loop" rendition of this problem will appreciate the interactivity of this applet simulation. All relevant physical quantities are clearly displayed.
Concerns:
The simulation does not allow the user to follow the wavepacket for very long distances or times. This may inhibit understanding of some of the related physical concepts. The item lacks sufficient discussion of what the expected long term behavior of the gaussian wave packet should be. However, other items within this collection deal with these issues.
Potential Effectiveness as a Teaching Tool
Rating:
Strengths:
Recommended Uses for Material: Lecture/Demo & Tutorial
The applet allows four available barrier heights that illustrate the relevant physical principles very well. There is a bit of textual explanation that is clear and concise.
This is a very well done applet that illustrates several core ideas in elementary quantum mechanics, including tunneling and propagation into the classically forbidden region. The use of physical units corresponding to a real physical system avoids the abstractness of normalized units. Will be most effective when used as a component in conjunction with the rest of this Meta Site.
Concerns:
The wavepacket on the left does not "appear" to spread in the the time viewed. The long time asymptotic results can be important, but are not clearly displayed, indicated or discussed.
Ease of Use for Both Students and Faculty
Rating:
Strengths:
The applet is very well organized and is very aesthetically done. Intuitive and easy to use.
Creative Commons:
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