Bose Einstein condensate/ atom laser

[Feynmanbest]

Dear,

I am reading a paper on Bose Einstein condensate and an atom laser. I have two questions which are bothering me for a time.

- When you are going to make do all the atoms start with the same the Broglie wavelenghts or do they start with different wavelenghts due to different energie's?

- I read about an atom laser using the stern garlach effect where they say: "All the atoms have their (electron) spin up and are lined up in the magnetic field". The atoms are bosons but the electron are under the power of the exclusion principle of paule how can they all have the same spin?

Sorry if my questions are unclear
Thanks! ;)

 

[EmpaDoc]

First question, the (simplified) answer is that: They have the same de Broglie wavelength. Otherwise it would not be a BEC.
(In fact, they need not have a definite dB wavelength; but they should all be in the *same quantum state* which can be a superposition of different wavelengths.)

Second question: A bosonic atom consists of an even number of fermions (electrons + protons + neutrons). The "electron spin" of the atom is the *sum* of the spins of all electrons and these can be lined up, even though two individual electrons are not in the same state.