Eur. Phys. J. D 31, 273-282 (2004)
https://doi.org/10.1140/epjd/e2004-00122-3

New directions in degenerate dipolar molecules via collective association

¹ QUANTOP–Danish National Research Foundation Center for Quantum Optics, Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
² Helsinki Institute of Physics, PL 64, 00014 Helsingin yliopisto, Finland
³ School of Pure and Applied Physics, University of KwaZulu-Natal, Durban 4041, South Africa
⁴ Department of Physics, University of Turku, 20014 Turun yliopisto, Finland
⁵ Department of Physics, University of Connecticut, Storrs, Connecticut, 06269-3046, USA

Corresponding author: ^a mattmackie2000@yahoo.com

Received: 16 June 2004
Published online: 21 September 2004

Abstract

We survey results on the creation of heteronuclear Fermi molecules by tuning a degenerate Bose-Fermi mixture into the neighborhood of an association resonance, either photoassociation or Feshbach, as well as the subsequent prospects for Cooper-like pairing between atoms and molecules. In the simplest case of only one molecular state, corresponding to either a Feshbach resonance or one-color photoassociation, the system displays Rabi oscillations and rapid adiabatic passage between a Bose-Fermi mixture of atoms and fermionic molecules. For two-color photoassociation, the system admits stimulated Raman adiabatic passage (STIRAP) from a Bose-Fermi mixture of atoms to stable Fermi molecules, even in the presence of particle-particle interactions. By tailoring the STIRAP sequence it is possible to deliberately convert only a fraction of the initial atoms, leaving a finite fraction of bosons behind to induce atom-molecule Cooper pairing via density fluctuations; unfortunately, this enhancement is insufficient to achieve a superfluid transition with present ultracold technology. We therefore propose the use of an association resonance that converts atoms and diatomic molecules (dimers) into triatomic molecules (trimers), which leads to a crossover from a Bose-Einstein condensate of trimers to atom-dimer Cooper pairs. Because heteronuclear dimers may possess a permanent electric dipole moment, this overall system presents an opportunity to investigate novel microscopic physics.