Spins Laboratory

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Use this virtual laboratory to build and run experiments to manipulate and measure the spins of quantum particles. The particle gun at left sends particles, one at a time, into experimental components that can include analyzers that direct the particles according to their spins, magnets that rotate the spins, and counters that record the arrival of particles. Initially you see a single analyzer with one counter connected to each of its output paths.

Instructions: Click or tap on a component’s output location (at its right side) to delete any existing connection and/or create a new one. Drag from there to the component you want to connect it to, or to an empty location to create a new component at that spot. If you send more than one path into the same analyzer then a checkbox will appear, allowing you to choose coherent or decoherent superpositions. To delete a component just drag it beyond the edge of the white area. To change the orientation of an analyzer or magnet, click/tap on the big letter and then select a choice from the menu that appears below. To change the strength/duration of a magnet, click on the number and adjust the slider. The buttons at the top of the particle gun send just one particle through, or 10,000 of them. The settings at the bottom determine the initial state of the emitted particles: R for random and 1,2,3,4 for four specific initial states that are for you to determine.

This version is a tweaked version of Dan Schroeder's "Spins" program: you can find the original version here. This particular version has been adapted for Six Ideas That Shaped Physics, unit Q: it only handles spin-1/2 quantons and one only needs real numbers to describe the unknown states 1, 2, and 3 (unknown state 4 requires complex numbers, and thus appendix QA).

This software is a work in progress. It has one known bug (really a physics error), often producing nonsensical results when paths from different components are combined and the “coherent” box is checked. Please report any other errors to Tom Moore using the contact form on the Six Ideas website.