# Why does strong magnetic field destroy spherical symmetry of atom?

1. Jan 8, 2009

### xfshi2000

In most of quantum textbook, they say strong magnetic field destroy the spherical symmetry of an atom in zeeman effect. Total angular moment is not conserved. Can anyone explain what physical meaning is? I cannot picture it in my mind. How does strong magnetic field cause spherical symmetry loss? thanks

2. Jan 8, 2009

### daschaich

The Zeeman effect involves the application of a static external magnetic field. This magnetic field singles out a particular direction, thus breaking spherical symmetry.

Symmetry will be broken no matter what the strength of the field, but at sufficiently weak field it may be possible to neglect the effects of symmetry breaking without introducing too serious errors.

If there's a particular reference that's confusing you, please share it so we can try to check it out.

3. Jan 8, 2009

### xfshi2000

Thank you for your kind reply. When I read quantum textbooks, I found a lot of stuff confuse me. For example:
(1) Photon has spin 1. But it only has two projections along the propagation direction. ms=(+/-)h bar. ms=0 is not existed because of transverse property of light. Dot product of vector k and polarization direction of photon epsilon should be zero. in textbook, they derive it in mathematical calculation. Does anyone give a physical picture about this case? Simply, a photon can be described by a plane wave. But we need modify the plane wave and multiply this plane wave by polarization direction of photon to construct photon wave function.

(2) This question also is related to zeeman effect. As we know, for ground state of hydrogen atom, S-state is splitted by external magnetic field. The transition between these two splitting energys generate a photon with different polarization radiation. Anyone can explain this radiation field of this transition? Such as the transition between different angular moment quantum number with same magnetic quantum number and the transition between same angular moment quantum number with different magnetic quantum number. Sometime a circularly polarized photon or linearly polarized photon from different view plane is generated. I don't know why? Anyone can comment that? thanks a lot.