Teaching Quantum Mechanics with PhET Simulations

1. Teaching Quantum Mechanics with PhET Simulations Sam McKagan, Katherine Perkins, Wendy Adams, Danielle Harlow, Michael Dubson, Chris Malley, Sam Reid, Ron LeMaster, Carl Wieman University of Colorado at Boulder http://phet.colorado.edu → Simulations → Quantum Phenomena QM Sims Addressing Common Student Difficulties PhET Project Overview • Examples: • We found that after classroom instruction on the Davisson Germer experiment, many students viewed the electrons as particles that happened to bounce off at certain angles for some reason they could not understand. The simulation helped them understand how the wave nature of light explained the results. • Many students confuse wave function and energy as a result of the common practice of drawing them on the same graph. Our simulations always display them separately. • Students may be misled by static representations of the real part of the wave function into thinking this is all there is. Our animated representations of the real part, imaginary part, and magnitude help students grasp the full complex time-dependent wave function in an intuitive, rather than mathematical way. • Many non-PhET QM simulations use phase color as the primary representation for complex wave functions. We have found that students cannot understand this representation without extensive instruction. Our sims use other representations that are easy for students to understand, with phase color as an advanced option. • The Physics Education Technology (PhET) Project is an on-going effort to create a suite of interactive simulations and related education resources that aid in the teaching and learning of physics. • Elaborate Java- and Flash-based simulations • Support for educators and students with resources for both teaching and learning with these simulations • Developed using the results of education research and feedback from educators • Research to formally assess their influence on student learning and attitudes in a variety of settings • A large number of simulations exist and are being used in introductory physics courses around the country • Can be used in lecture demonstrations, recitation activities, or homework assignments • All PhET simulations are free and available at http://phet.colorado.edu • New simulations in QM: • Allow students to explore and construct understanding of: • Fundamental principles of Quantum Mechanics • Key ideas in historical experiments • Quantum principles underlying everyday life applications. • Provide visual representations of abstract concepts and microscopic processes that cannot be directly observed • Help students to build mental models of phenomena that are often difficult to understand. PhET simulations in Quantum Mechanics Applications Fundamental Principles Classic Experiments CONTEXT INTERACTION ANIMATION VISUALIZATION See how photon behaves as a wave as it travels through space, and a particle when it hits the screen. Find the tumor. Change the spacing and radius of atoms Visualize not just the interference pattern on the screen, but the process that creates this pattern. Watch electron waves tunnel through barriers Conductivity Davisson Germer: Electron Diffraction Simplified MRI Quantum Wave Interference Quantum Tunneling See electrons jump energy levels. See electron waves diffract off atoms Semiconductors Visualize phenomena that you can’t observe directly, such as atomic excitations, electrons, and photons Quantum Bound States Photoelectric Effect Discharge Lamps Fire the photon gun Grab the semiconductors and put them in the circuit See electrons ejected from plate with varying speeds. Watch them speed up or slow down when voltage is applied. Configure your atom’s energy levels Directly manipulate potential with drag handles and get instant feedback on how this changes energy levels and wave functions Lasers Nuclear Physics Laser explodes if it builds up too much power. Invite to interact PhET is Free! You can download sims & activities from the PhET website! Visit the PhET BoothPlay with the simsUse them this fall See time evolution of wave functions Double Wells and Covalent Bonding • New sims coming soon… • Stern-Gerlach Experiment • The Hydrogen Atom • Optical Tweezers • …and more! Band Structure View light as photons or waves. Compare and contrast these representations to get a complete picture. Set up a chain reaction Student Responses to Quantum Sims Teaching with PhET simulations In-Class/Lecture Homework “Great sims, I can't imagine QM without them.” “The simulations were crucial in the learning process.” “The simulations were the best part of class, they practically answer physics questions all by themselves. I would recommend continuing to develop these and add more. Without these I think I would have been lost in the course.” “I definitely not only enjoyed the simulations, but I'd go as far to say that the simulations taught me the most about the course because I could really visualize the inner workings of the physics processes that we going on.” “I thought the simulations were great. It helped me to gain intuition about the topic. This is especially useful in quantum mechanics where • Use the sims as… • an effective means of communicating the instructors’ visual model to the students. • a means for interactive engagement within class using the Peer Instruction model with simulation-centered concept tests or interactive lecture demos. • a complementary learning-support tool for classroom demos. • a short pre-class activity to prepare students for class. • Use the sims as… • a method to promote active thinking with inquiry-based exercises designed around the simulations. • an alternative to or supplement for traditional introductory physics labs. Photoelectric Effect Sample Homework Problems Lasers: it is not normally possible to directly observe the described phenomena.” “The photon ray gun I first saw in lecture and that was very important to understanding the spread out nature of photons. I used the laser simulation on my own first and had to play with it to get it to lase, which was a good learning experience.” “This is what really clarified the difference between P and N-type and to figure out what orientation/arrangement is required for a LED to work.” “I related to this, for my mother has brain cancer. She has MRIs frequently as you could imagine. Now I know what is really going on every time she has one done.” Sample Concept Test Student Responses: Discharge Lamps Instructors observed that most students did not know the correct answer initially, but many were able to figure it out through discussion. Graphs that students drew, before seeing multiple choice options, closely matched given options. Acknowledgements Quantum Wave Interference The authors thank the Hewlett Foundation, NSF, and the Kavli Operating Institute for providing the support for the PhET Project. We also thank all the members of the PhET Team and the Physics Education Research at Colorado group (PER@C).