Dissociation dynamics of a Bose-Einstein condensate of molecules

Abstract

An unstable condensate of diatomic molecules will coherently disassociate into correlated pairs of atoms. This dissociation process exhibits very rich quantum dynamics depending on the quantum statistics of the constituent atoms. We show that in the case of bosonic atoms Bose-enhancement can lead to stimulated dissociation, whereas, in the case of fermions Pauli-blocking of the available states and a build-up of coherence between molecules and atom pairs can give rise to incomplete dissociation of the molecules and transient association-dissociation oscillations.Comment: 5 pages, 3 figures. to appear in PR

Role of spatial inhomogeneity in dissociation of trapped molecular condensates

“…This is a challenging task yet to be realized experimentally. In the case of fermionic statistics of the constituent atoms, dissociation of a molecular BEC offers a new paradigm of fermionic quantum atom optics [36,37] and new opportunities for extensions of fundamental tests of quantum mechanics to ensembles of neutral fermionic atoms.…”

“…In the short-time limit, the converted fraction of molecules into constituent atoms is small and one can employ the undepleted molecular-field approximation, which was successfully used in theoretical descriptions of parametric down-conversion in quantum optics [38]. Even though a less restrictive description of dissociation dynamics can be accomplished via state-of-the-art numerical techniques, such as the first-principles simulations using the positive-P and Gaussian representations [39][40][41][42][43], the truncated Wigner function approach [42], the Hartree-FockBogoliubov method [37,42,44], and a generalized GrossPitaevskii (GP) equation [45], the main motivation of the present work is to obtain approximate analytic results which are less computationally expensive and have the intrinsic appeal of analytic simplicity. By comparing these results with the numerical ones, one can verify their accuracy and the range of validity in different parameter regimes.…”

Spatial Pair Correlations of Atoms in Molecular Dissociation

“…There is also a need to determine the best operational measures [12,18] of correlations for these experiments. The present work is a step towards these goals, and a benchmark for other (approximate) theories.Previous theoretical work on molecular dissociation has explored the atomic correlations in simplified cases such as 1D systems [7,9], without depletion of the molecules during conversion [12], or for spatially uniform systems [11,18]. The present work builds on the characterization of the atomic correlations in momentum space in Ref.…”

“…Previous theoretical work on molecular dissociation has explored the atomic correlations in simplified cases such as 1D systems [7,9], without depletion of the molecules during conversion [12], or for spatially uniform systems [11,18]. The present work builds on the characterization of the atomic correlations in momentum space in Ref.…”

“…This has been demonstrated experimentally using ultracold (but not Bose condensed) 87 Rb 2 dimers [10], although the atom correlations have not yet been measured. In the case of fermionic atoms [11,12], such as in dissociation of 40 K 2 dimers [13], the densitydensity correlations between the atoms in two different spin states have been measured; this case, however, currently resists first-principles quantum simulations. Nevertheless, many insights from the present bosonic case also apply to the fermionic case, and to correlations produced via BEC four-wave mixing [14].…”