Ultracold lithium-rubidium molecules

Leader: Dr Xinyu Luo

The ultracold lithium-rubidium project will explore the rich phase diagram of a degenerate Fermi gas of polar molecules near a field-linked scattering resonance, including the long-sought dipolar p-wave superfluid of fermionic diatomic molecules, the Bose-Einstein condensate (BEC) of tetermer molecules, and the crossover/transition in between. For this purpose, we will first create a new species of 6Li87Rb polar molecules in the quantum degenerate regime. This new kind of bialkali molecules is promising for its highly tunable interaction and its potential to reach unprecedentedly cold temperature. Both are essential to realize the dipolar superfluid and the BEC of tetramers.

Specifically, we will

• Realize a deeply degenerate Fermi gas of new species of 6Li87Rb molecules with flexible control of dipolar interactions via field-linked resonances that was recently demonstrated in my group.
• Realize and explore dipolar p-wave superfluids featuring anisotropic pairing with non-zero angular momentum in polar molecule systems.
• Realize and explore the Bose-Einstein condensate of tetramers which exhibits both strong dipolar and quadrupolar interactions, including the crossover/transition from a dipolar superfluid to a tetramer BEC.

We propose DiMoBecTe at an exciting time when degenerate Fermi gases of polar molecules have finally become available in experiments, including degenerate NaK molecules attained in my group. It will provide a brand new platform to understand and design unconventional p-wave superfluidity with highly controllable interactions, and to realize Majorana modes in polar molecule systems and therefore pave the way towards topologically protected quantum computation. Furthermore, it will, for the first time bring polyatomic molecules into the quantum degenerate regime by creating a BEC of tetramer molecules.

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