Non-adiabatic quantum interference and complex formation in ultracold collisions of Rb with KRb

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Chemistry
• Chemical Physics

Background:

• Ultracold collisions are crucial for quantum simulation and ultracold chemistry.
• Understanding scattering dynamics requires accurate potential energy surfaces and quantum mechanical treatments.
• Previous studies lacked detailed theoretical insights into non-adiabatic effects in ultracold alkali-metal molecule collisions.

Purpose of the Study:

• To investigate ultracold elastic collisions between 87Rb and 40K87Rb.
• To compute elastic scattering cross sections, rate coefficients, and collision lifetime spectra.
• To elucidate the role of non-adiabatic couplings and conical intersections in collision dynamics.

Main Methods:

• First principles theoretical methodology.
• Full-dimensional ab initio potential energy surfaces for two electronic states.
• Numerically exact time-independent quantum dynamics in hyperspherical coordinates.
• Two-state diabatic representation for electronic states and non-adiabatic couplings.

Main Results:

• Accurate potential energy surfaces including conical intersection and long-range behavior were computed.
• Elastic scattering cross sections, rate coefficients, and collision lifetime spectra were calculated.
• The computed elastic rate coefficient shows good agreement with experimental data.
• Significant non-adiabatic quantum interference effects were observed.
• The origin of long-lived 3-body collision complexes was investigated.

Conclusions:

• The theoretical methodology accurately describes ultracold elastic collisions.
• Non-adiabatic quantum interference, influenced by a conical intersection's geometric phase, plays a significant role.
• The study provides insights into the formation of long-lived 3-body collision complexes in ultracold atomic systems.