Question

31. To achieve the Bose–Einstein condensation requires very low temperatures (so that the atoms are moving very slowly and thus have large de Broglie wavelengths) and low densities (so that the atoms don’t condense into an ordinary solid). For the atoms to behave as if they are in a single quantum state, their de Broglie wavelength must be about the same as the distance between atoms, so that their wave packets overlap. (a) Calculate the atomic spacing for a gas of density 5 × 10¹² atoms/cm³, which was the density used in the experiments of Wieman and Cornell shown in Figure 10.21. (b) Calculate the temperature at which the ⁸⁷Rb gas molecules would have a de Broglie wavelength equal to the atomic spacing.

Answer 1