Can a Bose gas be saturated?

Abstract

Bose-Einstein condensation is unique among phase transitions between different states of matter in the sense that it occurs even in the absence of interactions between particles. In Einstein's textbook picture of an ideal gas, purely statistical arguments set an upper bound on the number of particles occupying the excited states of the system, and condensation is driven by this saturation of the quantum vapour. Dilute ultracold atomic gases are celebrated as a realisation of Bose-Einstein condensation in close to its purely statistical form. Here we scrutinise this point of view using an ultracold gas of potassium (39K) atoms, in which the strength of interactions can be tuned via a Feshbach scattering resonance. We first show that under typical experi-mental conditions a partially condensed atomic gas strongly deviates from the textbook concept of a saturated vapour. We then use measurements at a range of interaction strengths and temperatures to extrapolate to the non-interacting limit, and prove that in this limit the behaviour of a Bose gas is consistent with the saturation picture. Finally, we provide evidence for the universality of our observations through additional measurements with a different atomic species, 87Rb. Our results suggest a new way of characterising condensation phenomena in different physical systems.

6 pages, 5 figures

References in corpus (11)

• Theory of Bose-Einstein condensation in trapped gases
• Feshbach Resonances in Ultracold Gases
• Bose-Einstein condensation of photons in an optical microcavity
• Disordered quantum gases under control
• Observation of an Efimov spectrum in an atomic system
• 39-K Bose-Einstein condensate with tunable interactions
• The critical temperature of a trapped, weakly interacting Bose gas
• Observation of deviations from ideal gas thermodynamics in a trapped Bose-Einstein condensed gas
• Bose-Einstein condensation at constant temperature
• Efficient Production of Large 39K Bose-Einstein Condensates
• Obtaining phase diagram and thermodynamic quantities of bulk systems from the densities of trapped gases

Cited by in corpus (29)

• Quantum Gases in Optical Boxes
• Nonequilibrium Model of Photon Condensation
• Effects of Interactions on the Critical Temperature of a Trapped Bose Gas
• Bose-Einstein condensation of paraxial light
• Theory of excitation of Rydberg polarons in an atomic quantum gas
• Quantum Joule-Thomson Effect in a Saturated Homogeneous Bose Gas
• Emergence of isotropy and dynamic scaling in 2D wave turbulence in a homogeneous Bose gas
• Compressibility and the Equation of State of an Optical Quantum Gas in a Box
• Thermally Condensing Photons into a Coherently Split State of Light
• Calorimetry of a Bose-Einstein condensed photon gas
• Condensed Fraction of an Atomic Bose Gas Induced by Critical Correlations
• Observation of Microcanonical Atom Number Fluctuations in a Bose-Einstein Condensate
• Bose-Einstein Condensation in a Dilute, Trapped Gas at Positive Temperature
• Measurement of the Canonical Equation of State of a Weakly Interacting 3D Bose Gas
• Finite temperature phase diagram of a spin-1 Bose gas
• Gross-Pitaevskii Limit of a Homogeneous Bose Gas at Positive Temperature
• Condensation dynamics in a quantum-quenched Bose gas
• Competition between Bose Einstein Condensation and spin dynamics
• Observing atom bunching by the Fourier slice theorem
• Increasing Quantum Degeneracy by Heating a Superfluid
• A superheated Bose-condensed gas
• Semiclassical Hartree-Fock theory of a rotating Bose-Einstein condensation
• Scaling of Fluctuations in a Trapped Binary Condensate
• Dissipative Distillation of Supercritical Quantum Gases
• On the fluctuations of the number of atoms in the condensate
• Calorimetry of a harmonically trapped Bose gas
• Can three-body recombination purify a quantum gas?
• Self-Bayesian Aberration Removal via Constraints for Ultracold Atom Microscopy
• Interacting Bose-condensed gases