Re: Quantum reflection shields ultracold atoms

From: Gregory L. Hansen (glhansen_at_steel.ucs.indiana.edu)
Date: 08/03/04 

Date: Tue, 3 Aug 2004 14:06:58 +0000 (UTC)

In article <410EF32C.4DDB2D8A@mchsi.com>,
Sam Wormley <swormley1@mchsi.com> wrote:
>Ref: http://physicsweb.org/article/world/17/8/4
>
>When a ball rolls down a hill, the last thing you expect is for it to
> suddenly stop and then roll straight back up the hill. At the atomic
> scale, however, the wave nature of particles becomes important and can
> lead to a counterintuitive phenomenon called quantum reflection. This is
> a purely quantum- mechanical process in which a particle moving in a
> given direction can reverse its direction of motion without reaching a
> classical turning point. It is thus the counterpart of quantum
> tunnelling, in which a particle can penetrate a potential barrier in a
> way that is forbidden by classical mechanics.
>
>See: http://physicsweb.org/article/world/17/8/4

But is it newsworthy? It's been a standard peice in textbooks for
probably about 80 years. In addition, particles can reflect from
attractive potentials. Like any wave mechanics, quantum wave packets
reflect from rapid changes in the impedence/index of refraction/potential. 

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"And don't skimp on the mayonnaise!"

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