Peer Review

1-D Quantum Transitions Applet

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Reviewed:: Feb 1, 2007 by Physics

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Ratings

Overall Rating:

Content Quality:

Effectiveness:

Ease of Use:

Overview:: This Java applet simulates quantum-mechanical transitions due to interactions with a classical electromagnetic field. The systems illustrated are bound states in four one-dimensional quantum-mechanical wells: the infinite square well, the finite square well, the harmonic oscillator, and the coupled well. The user has control over the amplitude and phase of the energy eigenstates in the quantum state and the magnitude and frequency of the field. The time dependence of a wide range of physical properties, including energy, momentum, current, and uncertainty can be displayed.
Type of Material:: Java simulation
Recommended Uses:: Lecture/demonstrations and illustrations for tutorials or homework.
Technical Requirements:: Java enabled browser is required
Identify Major Learning Goals:: Develop student understanding of time dependent potentials and quantum transitions.
Target Student Population:: Upper level undergraduates and graduate students. Can be used as a qualitative example in lower level modern physics or chemistry courses.
Prerequisite Knowledge or Skills:: An introduction to 1D quantum bound states and basic quantities such as wavefunctions, expectation values, and uncertainties.

Content Quality

Rating:

Strengths:

This applet illustrates an aspect of quantum physics that is difficult to display and, for many students to understand. The time-dependent properties of states in a time-dependent field are often not well covered in quantum mechanics classes, but are of great importance for understanding measurements of real systems. Radiative transitions of quantum states are clear indications of the discrete nature of bound state energies.

The ability of the user to control the simulated system is important for exploring the physics. By changing the populated states, one can see the different allowed and forbidden transitions. By changing the frequency and amplitude of the oscillating field, one can explore resonance and the important parameters that determine the transitions between states.

The comprehensiveness and flexibility of this applet makes it useful for almost any advanced quantum mechanics course.

Concerns:

This applet is qualitative in nature, so it can not be compared directly with the results of calculations. For example, the phasors illustrate the relative population of each of the states, but because they are not numerical one can't compare the time-dependent simulation with time-dependent perturbation theory calculations.

Potential Effectiveness as a Teaching Tool

Rating:
Strengths:: This general purpose applet can illustrate a wide variety of time-dependent physical scenarios in one-dimensional quantum mechanics. This is physics that students have probably never seen presented in such a clear way. The graphical display and ability to change parameters will engage the students.
Concerns:: The lack of curricular material written for these applets limits their usefulness to instructors. Tutorial materials or example problems must be created by the instructor.

Ease of Use for Both Students and Faculty

Rating:
Strengths:: This applet includes user interface elements that allow students to interact with the applet. The drop-down menus and mouse-actions allow the user to set up almost any configuration and explore its evolution. The graphical nature of the applet makes use straight.
The instructions for running the applet are well written and complete.
Concerns:: The interface displays a great deal of information. Clicking on different screens in the display can change the state of the object in ways that the student might not understand.
The applet would be more useful with curricular materials that would exploit the applets strengths.

Other Issues and Comments:: This is a unique and well designed simulation that illustrates a topic that tends to be poorly covered in textbooks. It leverages quite well the multimedia capabilities of Java.
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