Experiments with Supersonic Beams as a Source of Cold Atoms
Experiments with Supersonic Beams as a Source of Cold Atoms
Experiments with Supersonic Beams as a Source of Cold Atoms
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Chapter 3<br />
Slowing <strong>Supersonic</strong> <strong>Beams</strong> via Specular Reflection:<br />
The Atomic Paddle<br />
As experimental control <strong>of</strong> atomic motion h<strong>as</strong> improved, the wave nature <strong>of</strong><br />
atomic beams h<strong>as</strong> become an important factor in many experiments. Quantum me-<br />
chanics states that like light, matter is both a particle and a wave. This h<strong>as</strong> given<br />
birth to a new cl<strong>as</strong>s <strong>of</strong> experiments which exploit the wave nature <strong>of</strong> atoms and ma-<br />
nipulate beams <strong>of</strong> atoms in a particle analog to optical manipulation <strong>of</strong> beams <strong>of</strong><br />
light. This growing field is known <strong>as</strong> atom optics, and much research h<strong>as</strong> recently<br />
gone into developing a toolbox for manipulating atomic beams.<br />
Most <strong>of</strong> the work in atom optics h<strong>as</strong> used l<strong>as</strong>er cooled atoms [38, 39], which<br />
provide several advantages. Since the atoms are l<strong>as</strong>er cooled they are quite cold, and<br />
beams can be produced at low velocities. This accentuates the wave nature <strong>of</strong> the<br />
particles, <strong>as</strong><br />
λ = 2π<br />
(3.1)<br />
p<br />
where λ is the de Broglie wavelength <strong>of</strong> a particle, and p is the particle’s momentum.<br />
Furthermore, l<strong>as</strong>er cooled atoms have an accessible transition an experimentalist can<br />
use to both manipulate and detect the atoms in the beam. There are some drawbacks<br />
to using l<strong>as</strong>er cooled atoms however, most notably their sensitivity to stray fields.<br />
It is rather difficult to effectively control the atomic motion <strong>of</strong> ground state<br />
helium, due to the lack <strong>of</strong> accessible transitions <strong>with</strong> current l<strong>as</strong>er technology. How-<br />
ever, helium is known to reflect well from single crystal surfaces [40], which suggests<br />
20