Nanoprobes, spectroscopy and scattering 2004: ultracold gases

Introduction

The magneto-optical trap (MOT) is the workhorse of modern cold-atom physics. It has only modest experimental requirements (laser beams from a few directions, two coils generating a magnetic field, reasonable vacuum), yet trapped samples of gaseous atoms at temperatures below a millikelvin are easily reached. The MOT uses the scattering force associated with absorption and spontaneous emission of light by atoms. It is the basis of nearly all current ultracold-gases experiments worldwide.

The collisions among the atoms are essential for further (evaporative) cooling and for the resulting quantum-degenerate gases (Bose-Einstein condensates and/or degenerate Fermi gases).

Classroom

In two class-room sessions, led by dr. Robert Spreeuw and dr. Klaasjan van Druten the basic ingredients and requirements of the magneto-optical trap will be discussed.
In the following two sessions, the collisional properties are discussed of the ultracold atoms that result from further (evaporative) cooling, by prof. dr. Jook Walraven.

Experiment

A working magneto-optical trap (using rubidium) will be demonstrated and discussed with small groups of students, after which the students will get hands-on experience with adjusting a wide range of experimental knobs and parameters and see the effect on the MOT for themselves. Preparation for the experiments (should take about half an hour): see here.

Homework

Homework assignments will be handed out during the lectures.

Research articles

The following research articles are suggested for presentation by the students.

• Raab et al., Physical Review Letters 59, 2631 (1987) (local PDF), (online journal abstract).
  First demonstration and discussion of the magneto-optical trap (MOT).
• Reichel et al., Physical Review Letters 83, 3398 (1999). (local PDF), (online journal abstract).
  First demonstration and discussion of the mirror-MOT.
• Gibble et al., Optics Letters 17, 526 (1992). (local PDF),
  MOT with large atom number
• Vengalattore et al., Physical Review Letters 92, 183001 (2004). (local PDF), (online journal abstract).
  Enhanced phase-space density in a MOT.
• Buggle et al., arXiv condmat/0406093 (2004). (local PDF), (online abstract).
  Demonstration of the use of interference between s- and d-wave scattering of ultracold atoms for determining collisional parameters.

Schedule

Lectures:

1. Thursday September 9, 13.00-17.00h
2. Monday September 13, 13.00-17.00h
3. Thursday September 16, 13.00-17.00h
4. Monday September 20, 13.00-17.00h

Experiments: morning or afternoon session; the following dates are available:

1. Wednesday, September 15, morning
2. Wednesday, September 22, morning or afternoon
3. Wednesday, September 29, morning or afternoon
4. Wednesday, October 6, morning or afternoon
5. Wednesday, October 20, morning or afternoon

Further reading:

1997 Nobel lectures:

• Steven Chu, Reviews of Modern Physics 70, 685 (1998). (local PDF), (online journal).
  
• Claude N. Cohen-Tannoudji, Reviews of Modern Physics 70, 707 (1998). (local PDF), (online journal).
• William D. Phillips, Reviews of Modern Physics 70, 721 (1998). (local PDF), (online journal).

Book: Harold J. Metcalf and Peter van der Straten, Laser Cooling and Trapping, Springer (1999).

Weblinks

Quantum Gases - Atom Optics group
Atom traps worldwide