Difference between revisions of "Light forces"

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In preparation for 2009.
 
 
* [[Light forces from steady-state solutions]]
 
* [[Dipole force and dissipation]]
 
 
 
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== Handouts ==
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This chapter introduces the interaction of motional degrees of freedom with light and internal atomic states.  We begin by re-visiting the optical Bloch equations, and show how that formalism already includes the basis for inclusion of spatial coordinates in the equations of motion.  In particular, we show that the steady state solutions of the optical Bloch equations lead to a nice picture of how atoms excited by an electromagnetic field can feel a friction force.  This formalism provides a basis for an exploration of laser cooling, due to the balance of momentum absorbed from light and momentum released in random directions through spontaneous emission.  We find that this "spontaneous light force" mechanism is responsible for three important modern laser cooling techniques, optical molasses, beam slowing, and magneto-optical traps.  When a very strong light field is applied, the dynamics change, allowing the dipole force of a light beam to manipulate atoms (even single atoms!) through a potential due to the AC Stark shift, as is seen through the dressed atom picture.
  
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* [[Light forces from steady-state solutions]] ([https://cua-admin.mit.edu:8443/wiki/images/8/88/2009-04-06-Light_Forces.pdf 2009 Class notes])
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* [[Applications of the spontaneous light force]] ([https://cua-admin.mit.edu:8443/wiki/images/a/aa/2009-04-08-Applications_of_spontaneous_force.pdf  2009 Class notes])
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** [[Optical Molasses]]
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** [[Beam Slowing]]
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** [[Magneto-Optical Traps]]
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* [[Dipole forces and the dressed atom picture]]
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** [[Dressed atom approach]]  ([https://cua-admin.mit.edu:8443/wiki/images/c/c8/2009-04-17-Dressed_Atoms.pdf 2009 Class notes])
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** [[Dipole forces within the dressed atom approach]] ([https://cua-admin.mit.edu:8443/wiki/images/b/b8/2009-04-22_Stimulated_forces.pdf 2009 Class notes])
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* [[Sub-Doppler cooling]]  ([https://cua-admin.mit.edu:8443/wiki/images/1/1f/2009-04-27-Sub_Doppler_Cooling.pdf 2009 Class notes])
  
* Mean radiation forces API pp. 370 - 379
 
** Further reading on friction force in a standing wave
 
** C. Cohen-Tannoudji, Les Houches 1990, pp. 34-35
 
** J.P. Gordon and A. Ashkin, PRA 21, 1606 (1980)
 
* The dressed atom approach
 
**            Reading:  API Chapter VI – worth reading!
 
* Dipole forces within the dressed atom picture
 
** Lecture notes
 
** Important paper: J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. Am .B 2, 1707 (1985)
 
* Spontaneous light force traps
 
** Magneto-optical trap, Optical Earnshaw theorem
 
** Reading:  pp. 316-335 of the paper which was already used in lecture 1
 
***            (Nice summary on both dipole traps and radiation pressure traps)
 
**** W.D. Phillips, Laser cooling and trapping of neutral atoms, in Laser Manipulation of Atoms and Ions, edited by E. Arimondo, W.D. Phillips, and F. Strumia, Proceedings of the International School of Physics “Enrico Fermi”, Course CXVIII (North-Holland, Amsterdam, 1992) Download
 
*** Original papers:
 
****            Optical Earnshaw theorem (OET):  Ashkin and Gordon
 
****            How to circumvent the OET:  Pritchard et al.
 
****            Realization of the MOT:  Raab et al.
 
  
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Latest revision as of 20:14, 13 December 2013

This chapter introduces the interaction of motional degrees of freedom with light and internal atomic states. We begin by re-visiting the optical Bloch equations, and show how that formalism already includes the basis for inclusion of spatial coordinates in the equations of motion. In particular, we show that the steady state solutions of the optical Bloch equations lead to a nice picture of how atoms excited by an electromagnetic field can feel a friction force. This formalism provides a basis for an exploration of laser cooling, due to the balance of momentum absorbed from light and momentum released in random directions through spontaneous emission. We find that this "spontaneous light force" mechanism is responsible for three important modern laser cooling techniques, optical molasses, beam slowing, and magneto-optical traps. When a very strong light field is applied, the dynamics change, allowing the dipole force of a light beam to manipulate atoms (even single atoms!) through a potential due to the AC Stark shift, as is seen through the dressed atom picture.


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