Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The non-interacting Bose gas
- 3 Atomic properties
- 4 Trapping and cooling of atoms
- 5 Interactions between atoms
- 6 Theory of the condensed state
- 7 Dynamics of the condensate
- 8 Microscopic theory of the Bose gas
- 9 Rotating condensates
- 10 Superfluidity
- 11 Trapped clouds at non-zero temperature
- 12 Mixtures and spinor condensates
- 13 Interference and correlations
- 14 Optical lattices
- 15 Lower dimensions
- 16 Fermions
- 17 From atoms to molecules
- Appendix: Fundamental constants and conversion factors
- Index
17 - From atoms to molecules
Published online by Cambridge University Press: 25 January 2011
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The non-interacting Bose gas
- 3 Atomic properties
- 4 Trapping and cooling of atoms
- 5 Interactions between atoms
- 6 Theory of the condensed state
- 7 Dynamics of the condensate
- 8 Microscopic theory of the Bose gas
- 9 Rotating condensates
- 10 Superfluidity
- 11 Trapped clouds at non-zero temperature
- 12 Mixtures and spinor condensates
- 13 Interference and correlations
- 14 Optical lattices
- 15 Lower dimensions
- 16 Fermions
- 17 From atoms to molecules
- Appendix: Fundamental constants and conversion factors
- Index
Summary
A new facet was added to the study of dilute gases by the production and subsequent Bose–Einstein condensation of diatomic molecules from a gas of fermionic atoms. Feshbach resonances which, as we have seen in Sec. 5.4, make it possible to tune the atom–atom interaction, play a crucial role in the experiments. At the magnetic field strength for which the binding energy of the molecule vanishes, the inverse of the scattering length, which determines the low-energy effective interaction between atoms, passes through zero. In the experiments to produce molecules, one starts with a mixture of two species of fermion, most commonly different hyperfine states of the same isotope, in a magnetic field of such a strength that the molecular state has an energy higher than that of two zero-momentum atoms in the open channel. The magnetic field is then altered to a value at which the molecular state is bound with respect to two atoms in the open channel, and in this process, many of the atoms combine to form molecules. These molecules have binding energies in the 10−9 eV range, and are thus extremely weakly bound by the standards of conventional molecular physics. In addition, they are very extended, with atomic separations as large as one micron. These molecules, being bosons, can undergo Bose–Einstein condensation, just as bosonic atoms do.
- Type
- Chapter
- Information
- Bose–Einstein Condensation in Dilute Gases , pp. 514 - 561Publisher: Cambridge University PressPrint publication year: 2008