Bouncing electrons off a time mirror

Enlarge (credit: michael)

Time mirrors are very cool. They seem a bit magical, undoing the damage that time has done, at least under the right circumstances. For light and for water waves, we know how to make a mirror that behaves like it reverses time. But for quantum mechanical waves, some types of time mirrors have proven to be difficult. A recent theory paper suggests that, under the right circumstances, a mirror that undoes the past might be possible. And, it comes with a bonus movie.

Quantum time mirror. Video courtesy of Phillip Reck, University of Regensburg. (video link)

Before we get to the lovely movie and a bit of inexplicable quantum theory, let me give you a taste of what a time mirror means in a classical world.

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