Everything about Optical Lattice totally explained
An
optical lattice is formed by the
interference of counterpropagating
laser beams, which creates a periodic (in space)
intensity pattern. The resulting periodic
potential can then be used to trap neutral
atoms via the
Stark shift. Atoms are cooled and congregated in the potential minima. The resulting system of trapped atoms resembles a
crystal in the sense that the atoms are in a periodical potential.
Because of
quantum tunneling, atoms can move in the optical lattice even if the well depth of the lattice is higher than the energy of the atoms, which is similar to the electrons in a
conductor. However, there will be a
superfluid-Mott insulator transition if the interaction energy between the atoms becomes larger than the hopping
energy when the well depth is very large. In the
Mott insulator phase, atoms will be trapped in the potential minima and can not move freely, which is similar to the electrons in an insulator. Atoms in an optical lattice provide an ideal quantum system where all parameters can be controlled. Thus they can be used to study effects that are difficult to observe in real crystals. They are also promising candidates for
quantum information processing.
There are two important parameters of an optical lattice: the
well depth and the
periodicity. The well depth of the optical lattice can be tuned in
real time by changing the power of the laser, which is normally controlled by an AOM (
acousto-optic modulator). The
periodicity of the optical lattice can be tuned by changing the
wavelength of the laser or by changing the relative angle between the two laser beams. The real-time control of the periodicity of the lattice is still a challenging task. Because the wavelength of the laser can not be varied over a large range in real time, the periodicity of the lattice is normally controlled by the relative angle between the laser beams. However, it's difficult to keep the lattice stable while changing the relative angles, since the interference is sensitive to the relative
phase between the laser beams. Recently, a novel method of real-time control of the lattice periodicity was demonstrated, in which the center fringe moved less than 2.7 microns while the lattice periodicity was changed from 0.96 microns to 11.2 microns. Whether this method can keep atoms (or other particles) trapped while changing the lattice periodicity remains to be tested experimentally. Such
accordion lattices are useful for controlling untracold atoms in optical lattices, where small spacing is essential for quantum tunneling, and large spacing enables single-site
manipulation and spatially resolved
detection.
Besides of trapping cold atoms, optical lattices have been widely used in creating
gratings and
photonic crystals. They are also useful for sorting microscopic particles, and may be useful for assembling
cell arrays.
Further Information
Get more info on 'Optical Lattice'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://optical_lattice.totallyexplained.com">Optical lattice Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |