Phase diffusion between split atomic Bose-Einstein condensate (BEC)

Hongwei Xiong, Shujuan Liu, Guoxiang Huang

André F. Verbeure

Igor Tikhonenkov, Amichay Vardi

We study the collisional loss of atom-molecule coherence after coherently dissociating a small fraction of a molecular Bose-Einstein condensate into atoms. The obtained $n$-atoms states are two-atom (SU(1,1)) coherent states with number variance $Δn\propto n$ compared to $Δn\propto \sqrt{n}$ for the spin (SU(2)) coherent states formed by coherent splitting of an atomic condensate. Consequently, the Lorentzian atom-molecule phase-diffusion is faster than the Gaussian phase-diffusion between separated atomic condensates, by a $\sqrt{n}$ factor.

KL Lee, NB Jørgensen, I-Kang Liu +3 more

Juha Javanainen, Martin Wilkens

We analyze theoretically an experiment in which a trapped Bose-Einstein condensate is cut in half, and the parts are subsequently allowed to interfere. If the delay between cutting and atom detection is small, the interference pattern of the two halves of the condensate is the same in every experiment. However, for longer delays the spatial phase of the interference shows random fluctuations from one experiment to the other. This phase diffusion is characterized quantitatively.

Igor Tikhonenkov, Amichay Vardi

We propose to implement a sub-shot-noise matter-wave interferometer via the stimulated dissociation of a molecular Bose-Einstein condensate and study the collisional loss of atom-molecule coherence during its phase-acquisition time. The obtained $n$-atom states are two-atom [SU(1,1)] coherent states with number variance $\ensuremath{\Delta}n\ensuremath{\propto}n$ compared to $\ensuremath{\Delta}n\ensuremath{\propto}\sqrt{n}$ for the spin [SU(2)] coherent states formed by coherent splitting of an atomic condensate. Consequently, the Lorentzian atom-molecule phase diffusion is faster than the Gaussian phase diffusion between separated atomic condensates by a $\sqrt{n}$ factor.