Atomic hydrogen: the quantum gas

Quantum Boltzmann equation for atomic hydrogen

2014 The quantum Boltzmann equation governing the evolution of the one-body internal density matrix of an atomic hydrogen (or alkali) gas is established. Indistinguishability of both nuclei and electrons explains the presence in the collision term of a large number (eleven) of « exchange cross sections ». The different collision terms fall into two categories : these which contribute to the dam...

The Stabilization of Atomic Hydrogen : a New Bose Gas

Observation of quantum-measurement backaction with an ultracold atomic gas

Current research on micromechanical resonators strives for quantum-limited detection of the motion of macroscopic objects. Prerequisite to this goal is the observation of measurement backaction consistent with quantummetrology limits. However, thermal noise currently dominates measurements and precludes ground-state preparation of the resonator. Here, we establish the collective motion of an ul...

Intensity dependence of photoassociation in a quantum degenerate atomic gas.

We have measured the intensity dependent rate and frequency shift of a photoassociation transition in a quantum degenerate gas of 7Li. The rate increases linearly with photoassociation laser intensity for low intensities, whereas saturation is observed at higher intensities. The measured rates and shifts agree reasonably well with theory within the estimated systematic uncertainties. Several th...

Blocking of Collisions in a Quantum Degenerate Atomic Fermi Gas

We have produced an interacting quantum degenerate Fermi gas of atoms composed of two spin-states of magnetically trapped 40K. The relative Fermi energies are adjusted by controlling the population in each spin-state. Measurements of the thermodynamics reveal the resulting imbalance in the mean energy per particle between the two species, which is as large as a factor of 1.4 at our lowest tempe...