Book contents
- Frontmatter
- Contents
- Preface
- Preface to the second edition
- 1 Superconductivity and superfluidity
- 2 Mean-field theory of pair condensation
- 3 BCS theory
- 4 Superconductivity due to electron–phonon interaction
- 5 Ginzburg–Landau theory
- 6 Superfluid 3He
- 7 New superconducting materials
- Appendix 1 Bose–Einstein condensation in polarised alkaline atoms
- Appendix 2 Recent developments in research on high temperature superconductors
- References and bibliography
- Index
Appendix 1 - Bose–Einstein condensation in polarised alkaline atoms
Published online by Cambridge University Press: 23 December 2009
- Frontmatter
- Contents
- Preface
- Preface to the second edition
- 1 Superconductivity and superfluidity
- 2 Mean-field theory of pair condensation
- 3 BCS theory
- 4 Superconductivity due to electron–phonon interaction
- 5 Ginzburg–Landau theory
- 6 Superfluid 3He
- 7 New superconducting materials
- Appendix 1 Bose–Einstein condensation in polarised alkaline atoms
- Appendix 2 Recent developments in research on high temperature superconductors
- References and bibliography
- Index
Summary
Condensate in confining potential
This subject is directly related to Chapter 1 of this book and will be briefly summarised here although it has already been treated in an appendix of [E-11].
Spin polarised hydrogen H↓ is listed in the right hand column of Table 1.1 as a system predicted to show Bose-type superfluidity. Bose–Einstein condensation was observed, somewhat unexpectedly, in spin polarised alkaline gases Li↓, Na↓, and Rb↓, with quite an ingenious method using laser light, prior to observation in H↓ gas (see [H-1] – [H-3]). It is unquestionable that the macroscopic wave function appears although superfluidity has yet to be observed. See [H-4] for works on H↓, and related systems preceding this breakthrough.
In a typical experiment the magneto-optical trap, which we can approximate by an anisotropic 3-dimensional harmonic oscillator potential, is used to provide the confining potential for atoms. Its spatial scale is given by R ∼ (ħ/mω)½ ∼ 10−3m, where m is the mass of the atom while ω is the frequency of the harmonic oscillator. There are N ∼ 106 atoms trapped in a volume ∼ R3, for which the Bose–Einstein condensation temperature TBE given by Eq. (1.3) is of the order of 10−7 K for Rb atoms. It should be added that evaporation cooling, which has been used to cool H↓ gas, is required in addition to laser cooling to reach this temperature.
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- Superconductivity and Superfluidity , pp. 185 - 188Publisher: Cambridge University PressPrint publication year: 1998