Transition from an atomic to a molecular Bose-Einstein condensate.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Gases
• Condensed Matter Physics

Background:

• Ultracold and dense molecular gases are crucial for quantum applications but are difficult to prepare due to inelastic collisions.
• Reaching the quantum regime for molecules typically requires efficient cooling at high densities, a process often limited by molecular loss.

Purpose of the Study:

• To report the preparation of two-dimensional Bose-Einstein condensates (BECs) of spinning molecules.
• To investigate the transition between atomic and molecular condensates and explore superfluid properties.

Main Methods:

• Inducing pairing interactions in an atomic condensate near a g-wave Feshbach resonance.
• Utilizing a specific trap geometry and low molecular temperatures to minimize inelastic loss and ensure thermal equilibrium.
• Performing equation-of-state measurements to determine the molecular scattering length.

Main Results:

• Successfully prepared two-dimensional Bose-Einstein condensates (BECs) of spinning molecules.
• Determined the molecular scattering length to be +220(±30) Bohr radii.
• Observed unpairing dynamics consistent with the unitarity limit near the Feshbach resonance.

Conclusions:

• Demonstrated the transition between atomic and molecular condensates, analogous to the BEC-BCS crossover in Fermi gases.
• The findings may offer insights into condensed pairs with orbital angular momentum and anisotropic superfluids.
• This work opens avenues for quantum simulation, precision measurements, and quantum information processing.