Bose-Einstein condensate diagram

[Jufa]

TL;DR

Struggling with Bose-Einstein condensates diagram.

I have seen many of these diagrams in internet and I fail to figure out what their actual meaning is. Can someone explain what the axes and different colours mean? Also, which is the physical interpretation that can be extracted from them? Thanks in advance :).

 

[BvU]

many of these diagrams

You could add a reference !

You know what BE condensation means ?

Picture shows particle velocities. Color is density: number of particles with vx, vy in a cell. When it gets colder number of particles with vx=vy=0 increases: they all tend occupy the same QM ground state

 

[DrClaude]

The original data looks like

Observation of Bose-Einstein Condensation in a Dilute Atomic Vapor
M. H. Anderson, J. R. Ensher, M. R. Matthews, C. E. Wieman, E. A. Cornell
Science, v. 269, no. 5221 (1995), p. 198-201

These are false color images of the velocity distribution of the atoms in the clouds. The image you posted is the same data, but with an added height that is the same as the color map (in other words, color and height represent the same thing, namely the density of atoms with a given velocity).

 

[DrClaude]

Note that because Bose-Einstein in achieved here in a trap, the condensation happens not only in momentum space, but also in ordinary space. This is why the figure in the OP cheats a bit by presenting a spatial scale for what should be only velocities.

 

[Jufa]

You could add a reference !

You know what BE condensation means ?

Picture shows particle velocities. Color is density: number of particles with vx, vy in a cell. When it gets colder number of particles with vx=vy=0 increases: they all tend occupy the same QM ground state

If colour stands for the density, what is the height?

 

[BvU]

color = height

 

[DrClaude]

If colour stands for the density, what is the height?

(in other words, color and height represent the same thing, namely the density of atoms with a given velocity).

 

[Jufa]

Perfect, thanks! I do fully understand the diagram now.