Abstract
The following summary discusses the cooling techniques of atomic vapor in several different ways. Additionally, it tends to relate the evolution of experiments that are used in studying shallow layered fluids. Starting with the atomic condensates, the method is known as trapping. However, it exists in many ways from the laser system to the Bose-Einstein methods. The methods of cooling are different due to the evolutionary progress made by science. The use of laser beams includes the study of light forces on atoms which lead to either an absorption or emission of a photon. While the contraction of matter at the atomic level may seem fascinating, the theories in place have to be put into practicality with Bose suggesting that Chromium is better than the alkali metals in use. On the other hand, quasi-2D turbulences are proven not to be 2D but 3 D due to the tangential forces existing and may lead to a spontaneous spin –up of the constrained fluid making it go against its planar properties.
This article discusses the cold atom physics together with the Bose- Einstein condensation as it gives light to quantum metrology. The two main topics are coupled with several trap explanations including laser, magnetic and atom traps. In metrology, it is applicable due to the cooling of an atom for the appearance of the Doppler-free lines. The drop in temperature of an atom is essential when one needs to experiment with quantum physics of an atom
Light forces on atoms
Starting with the orders of magnitude we realize that light forces occur due to a recurrence of the changes in momentum at every photon transmission. Secondly, an atom is studied in the case of light iteration whereby we look at how light interact atoms where the state of excitation of an atom is applied in the Fermi – golden rule. And also, light force pressure being calculated and applied in the Zeeman slower which is enhancing the idea of using a laser that propagates against an atomic beam thus slowing it down almost to a stop. An application area is in Laser cooling. Additionally, there is the Doppler cooling where an atom is passed through a field of two laser beams. With a minimum temperature achieved as follows δ = −Γ/2 where α = αmax, known as the Doppler temperature.
Another way of cooling is known as the trapping method. It includes the magneto-optical trap which is conducted in a vacuum chamber 300 Kelvin in a fraction of a second. The other method of trapping is the conservative trapping.
Finally, looking into the Bose-Einstein condensation, in which we look into the transition temperature and the detection of BEC. In which the time of flight imaging is applicable. Additionally, while studying the coherence and atom laser, we realize that the coherence length of the condensate is equal to the size of the condensate.
TOPOLOGICAL PHASE IMPRINTING IN BEC IN THE PRESENCE OF GRAVITATIONAL FIELD
Alkali metal gas made of the BEC is confined in the very high magnetic field so as to create a vortex. The magnetic field can be the gravitational field in which the when the magnetic field makes the center of the condensate shift from the initial axis of the magnetic trap leading to the vortex fragmentation caused by the complex interaction between the two boundary states of the condensate.
THE QUASI- 2 D TURBULENCE
The 2D turbulence lacks the vortex unlike in 3D. However in recent experiments, the effect of lateral boundaries on the decaying 2D turbulence has got larger coherent vortex due to the inverse energy cascade leading to different decay rates. When an illustration of the decay is carried out in the lab, the interfacial region starts off as disorganized but after a while gets organized since the experiment is done in a square box with no-slip walls, thus implying the presence of boundary layers having very high concentrations of a vortex.
The article also highlights the effect of the vertical confinement of shallow-layer flows with proof that the fluid usually behaves in quasi -2D since the vertical component is smaller than the horizontal. The experiment is further made complex by looking into a solid bottom of the fluid container and thus bringing in the effect of the vertical gradient in the no-slip condition. The tangential forces created to make the liquid go into its planar formation with its constraints and develop into 3-D turbulence.
