English: Animation of a Hahn echo. Examples of the Hahn echo include the spin echo and the photon echo.
The red arrows can be thought of as spins. Applying the first pulse rotates the spins by 90 degrees, producing an equal superposition of spin up and spin down. The spins then "spread out" because each is in a slightly different environment. This spreading out looks like decoherence, but it can be refocused by a second pulse which rotates the spins by 180 degrees. Several simplifications are used in this animation: no decoherence is included and each spin experiences perfect pulses during which the environment provides no spreading. Animation made by Gavin W Morley with POV-Ray; some rights reserved. A bug in Wikipedia means this file does not animate if you scale it; a smaller version is available here: http://en.wiki.x.io/wiki/File:HahnEcho_GWM.gif. An animation with spin dephasing is shown here: http://commons.wikimedia.org/wiki/File:GWM_HahnEchoDecay.gif.
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
{{Information |Description ={{en|1=Animation of a Hahn echo. Examples of the Hahn echo include the spin echo and the photon echo. The red arrows can be thought of as spins. Applying the first pulse rotates the spins by 90 degrees, producing an equal
File usage
No pages on the English Wikipedia use this file (pages on other projects are not listed).