can greatly exceed the rate coefficient for heating and loss channels due to excited-state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time.

Related papers

Stimulated Raman molecule production in Bose-Einstein condensates

Paul S. Julienne, Keith R. Burnett, Y. B. Band +1 more

A Raman photoassociation process can be used to form translationally cold molecules from a Bose-Einstein condensate. Coupled-channels scattering calculations show that the rate coefficient for coherent production of molecules in specific target states, $>{10}^{\ensuremath{-}10} {\mathrm{cm}}^{3}/\mathrm{s},$ can greatly exceed the rate coefficient for heating and loss channels due to excited-state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time.A Raman photoassociation process can be used to form translationally cold molecules from a Bose-Einstein condensate. Coupled-channels scattering calculations show that the rate coefficient for coherent production of molecules in specific target states, $>{10}^{\ensuremath{-}10} {\mathrm{cm}}^{3}/\mathrm{s},$ can greatly exceed the rate coefficient for heating and loss channels due to excited-state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time.

Physical Review AAug 1, 1998105 citations

STIMULATED RAMAN MOLECULE FORMATION IN COLD ALKALI GASES.

Paul S. Julienne, Keith R. Burnett, Y. B. Band +1 more

Photoassociation is a process by which two cold, trapped atoms can be optically excited during a collision to make a vibrational level of an excited electronic state of a molecular dimer. High-resolution photoassociation spectra are now well-known for most alkali dimers. The upper level normally decays by spontaneous emission to a number of final molecular levels, bound and unbound. A laser of a second color can be used to stimulate a transition from the upper level to a particular ground state vibrational level. Such a Raman photoassociation process can be used to form translationally cold molecules in a cold atomic gas or a Bose-Einstein condensate. Coupled channels scattering calculations show that the collisional rate coefficient for coherent production of molecules in specific target states, $> 10^{-10} cm^{3}/s,$ can greatly exceed the rate coefficient for forming products due to excited state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time. The untrapped molecules can form a coherent molecular beam. We will examine the prospects for the experimental realization of photoassociative molecule formation in cold alkali gases or condensates.Photoassociation is a process by which two cold, trapped atoms can be optically excited during a collision to make a vibrational level of an excited electronic state of a molecular dimer. High-resolution photoassociation spectra are now well-known for most alkali dimers. The upper level normally decays by spontaneous emission to a number of final molecular levels, bound and unbound. A laser of a second color can be used to stimulate a transition from the upper level to a particular ground state vibrational level. Such a Raman photoassociation process can be used to form translationally cold molecules in a cold atomic gas or a Bose-Einstein condensate. Coupled channels scattering calculations show that the collisional rate coefficient for coherent production of molecules in specific target states, $> 10^{-10} cm^{3}/s,$ can greatly exceed the rate coefficient for forming products due to excited state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time. The untrapped molecules can form a coherent molecular beam. We will examine the prospects for the experimental realization of photoassociative molecule formation in cold alkali gases or condensates.

Jan 1, 19980 citations

Improved efficiency of stimulated Raman adiabatic passage in photoassociation of a Bose-Einstein condensate

Matt Mackie, Kari Härkönen, Anssi Collin +2 more

We theoretically examine Raman photoassociation of a Bose-Einstein condensate, revisiting stimulated Raman adiabatic passage (STIRAP). Due to collisional mean-field shifts, efficient molecular conversion requires strong coupling and low density, either of which can bring about rogue photodissociation to noncondensate modes. We demonstrate explicitly that rogue transitions are negligible for low excited-state fractions and photodissociation that is slower than the STIRAP time scale. Moreover, we derive a reduced-parameter model of collisions, and thereby find that a gain in the molecular conversion efficiency can be obtained by adjusting the atom-atom scattering length with off-resonant magnetoassociation. This gain saturates when the atom-atom scattering length is tuned to a specific fraction of either the molecule-molecule or atom-molecule scattering length. We conclude that a fully optimized STIRAP scheme may offer the best chance for achieving coherent conversion from an atomic to a molecular condensate with photoassociation.We theoretically examine Raman photoassociation of a Bose-Einstein condensate, revisiting stimulated Raman adiabatic passage (STIRAP). Due to collisional mean-field shifts, efficient molecular conversion requires strong coupling and low density, either of which can bring about rogue photodissociation to noncondensate modes. We demonstrate explicitly that rogue transitions are negligible for low excited-state fractions and photodissociation that is slower than the STIRAP time scale. Moreover, we derive a reduced-parameter model of collisions, and thereby find that a gain in the molecular conversion efficiency can be obtained by adjusting the atom-atom scattering length with off-resonant magnetoassociation. This gain saturates when the atom-atom scattering length is tuned to a specific fraction of either the molecule-molecule or atom-molecule scattering length. We conclude that a fully optimized STIRAP scheme may offer the best chance for achieving coherent conversion from an atomic to a molecular condensate with photoassociation.

arXiv:physics/0403070Physical Review AJul 28, 200439 citations

Stimulated Raman adiabatic passage from an atomic to a molecular Bose-Einstein condensate

P. D. Drummond, Karen V. Kheruntsyan

Summary form only given. Coherent conversion of an atomic to a molecular Bose-Einstein condensate (BEC) is a first step towards 'superchemistry', which is the atom optics analog of frequency conversion in nonlinear optics. A number of studies of this have shown that direct conversion via Raman photo-association appears feasible, based on stimulated free-bound and bound-bound transitions in the presence of two laser fields E/sup (1)/=E/sub 0//sup (1)/ cos(/spl omega//sup (1)/t) and E/sup (2)/=E/sub 0//sup (2)/ cos(/spl omega//sup (2)/t). Here pairs of atoms from the two-atom continuum are transferred-via an excited bound molecular state-to a bound molecular state of lower energy. Raman photo-association allows coupling to a single molecular state, which can be selected by the Raman laser frequencies /spl omega//sup (1)/ and /spl omega//sup (2)/. However, practical calculations using available lasers and transitions indicate that coherent transfer is often limited by spontaneous emission from the intermediate molecular excited electronic state. A possible route towards minimizing losses and decoherence from spontaneous emission is to use the stimulated Raman adiabatic passage (STIRAP) method (Drummond et al, Phys. Rev. Lett. vol. 81, p. 3055, 1998) in which a counter-intuitive pulse sequence is used where the first input pulse couples the molecular levels, even when there are no molecules present.Summary form only given. Coherent conversion of an atomic to a molecular Bose-Einstein condensate (BEC) is a first step towards 'superchemistry', which is the atom optics analog of frequency conversion in nonlinear optics. A number of studies of this have shown that direct conversion via Raman photo-association appears feasible, based on stimulated free-bound and bound-bound transitions in the presence of two laser fields E/sup (1)/=E/sub 0//sup (1)/ cos(/spl omega//sup (1)/t) and E/sup (2)/=E/sub 0//sup (2)/ cos(/spl omega//sup (2)/t). Here pairs of atoms from the two-atom continuum are transferred-via an excited bound molecular state-to a bound molecular state of lower energy. Raman photo-association allows coupling to a single molecular state, which can be selected by the Raman laser frequencies /spl omega//sup (1)/ and /spl omega//sup (2)/. However, practical calculations using available lasers and transitions indicate that coherent transfer is often limited by spontaneous emission from the intermediate molecular excited electronic state. A possible route towards minimizing losses and decoherence from spontaneous emission is to use the stimulated Raman adiabatic passage (STIRAP) method (Drummond et al, Phys. Rev. Lett. vol. 81, p. 3055, 1998) in which a counter-intuitive pulse sequence is used where the first input pulse couples the molecular levels, even when there are no molecules present.

Quantum Electronics and Laser Science ConferenceNov 13, 20021 citation

Stimulated Raman molecule production in a Bose-Einstein condensate

R. H. Wynar, R. S. Freeland, Changhyun Ryu +2 more

Summary form only given. We have created state-selected /sup 87/Rb/sub 2/ molecules at rest in a dilute Bose-Einstein condensate of /sup 87/Rb atoms with coherent free-bound stimulated Raman transitions. The transition lineshape exhibits a resonance lineshape with an extremely narrow width as small as 1.5 kHz. As a result, we are able to measure the molecular binding energy with an unprecedented precision of 1.2 kHz. We find that this lineshape is sensitive to elastic interactions between the molecules and the atomic Bose-condensate, and as a result, we are able to measure an atom-molecule scattering length for the first time. In addition, we are able to set an upper bound on the rate constant for inelastic collisions between the molecules and the atoms. This is the first measurement of molecule-condensate interactions, and is an important step towards the application of this method to the formation of a molecular Bose-Einstein condensate.Summary form only given. We have created state-selected /sup 87/Rb/sub 2/ molecules at rest in a dilute Bose-Einstein condensate of /sup 87/Rb atoms with coherent free-bound stimulated Raman transitions. The transition lineshape exhibits a resonance lineshape with an extremely narrow width as small as 1.5 kHz. As a result, we are able to measure the molecular binding energy with an unprecedented precision of 1.2 kHz. We find that this lineshape is sensitive to elastic interactions between the molecules and the atomic Bose-condensate, and as a result, we are able to measure an atom-molecule scattering length for the first time. In addition, we are able to set an upper bound on the rate constant for inelastic collisions between the molecules and the atoms. This is the first measurement of molecule-condensate interactions, and is an important step towards the application of this method to the formation of a molecular Bose-Einstein condensate.

Quantum Electronics and Laser Science ConferenceJan 1, 20000 citations

Observation of Bose-enhanced photoassociation products

A. Ciamei, Alex Bayerle, Benjamin Pasquiou +1 more

We produce 84 Sr 2 molecules using Bose-enhanced Raman photoassociation. We apply the stimulated Raman adiabatic passage (STIRAP) technique on a Bose-Einstein condensate (BEC) to produce more than 8 × 10 3 ultracold molecules. This chemical reaction is only made possible because of the Bose enhancement of the optical transition dipole moment between the initial atomic state and an intermediate molecular state. We study the effect of Bose enhancement by measuring the transition Rabi frequency in a BEC and by comparing it with measurements for two atoms in sites of a Mott insulator. By breaking the dimers' bond and directly observing the separated atoms, we measure the molecular inelastic collision rate parameters. We discuss the possibility of applying Bose-enhanced STIRAP to convert a BEC of atoms into a BEC of molecules, and argue that the required efficiency for STIRAP is within experimental reach.We produce 84 Sr 2 molecules using Bose-enhanced Raman photoassociation. We apply the stimulated Raman adiabatic passage (STIRAP) technique on a Bose-Einstein condensate (BEC) to produce more than 8 × 10 3 ultracold molecules. This chemical reaction is only made possible because of the Bose enhancement of the optical transition dipole moment between the initial atomic state and an intermediate molecular state. We study the effect of Bose enhancement by measuring the transition Rabi frequency in a BEC and by comparing it with measurements for two atoms in sites of a Mott insulator. By breaking the dimers' bond and directly observing the separated atoms, we measure the molecular inelastic collision rate parameters. We discuss the possibility of applying Bose-enhanced STIRAP to convert a BEC of atoms into a BEC of molecules, and argue that the required efficiency for STIRAP is within experimental reach.

arXiv:1708.00299Europhysics Letters (EPL)Aug 1, 20179 citations

g{10}^{\ensuremath{-}10} {\mathrm{cm}}^{3}/\mathrm{s},

> 10^{-10} cm^{3}/s,

can greatly exceed the rate coefficient for forming products due to excited state spontaneous decay. This implies the feasibility of rapid coherent conversion of atom pairs in a condensate to molecules on a time scale short compared to the trap oscillation time. The untrapped molecules can form a coherent molecular beam. We will examine the prospects for the experimental realization of photoassociative molecule formation in cold alkali gases or condensates.