Polar molecules enable the simula­tion of complex spin models and condensed matter phenom­ena due to their tunable long-range inter­ac­tions. This project aims to inves­ti­gate the transi­tion from a Bose-Einstein conden­sate of tetratomic molecules to a diatomic p‑wave super­fluid, referred to as BEC-BCS crossover. The super­fluid is of special inter­est as it is expected to host Majorana zero modes—quasi-particles ideal for fault-toler­ant topolog­i­cal quantum computing.

Recent progress in microwave shield­ing has improved control over inter­mol­e­c­u­lar inter­ac­tions, enabling polar molecules to reach the quantum degen­er­ate regime. This makes it the right time to exploit the molecules’ large dipole moments and complex inter­nal struc­tures for study­ing many-body physics. Creat­ing a Bose-Einstein conden­sate (BEC) of tetramers and transi­tion­ing to a Bardeen-Cooper-Schri­ef­fer (BCS) state of dimers require ultra­cold temper­a­tures in the nano-Kelvin range, while this novel BEC-BCS crossover is yet exper­i­men­tally unexplored. The p‑wave super­fluid emerg­ing in the BCS side provides insights into materi­als like ³He and high-temper­a­ture super­con­duc­tors. The px + ipy super­fluid phase is further­more topolog­i­cally non-trivial and expected to host Majorana zero modes (MZMs), quasi-parti­cles ideal for fault-toler­ant topolog­i­cal quantum comput­ing. Despite their long predic­tion, no defin­i­tive evidence for MZMs has been reported yet.

This project aims to create the px + ipy super­fluid and explore the BEC-BCS crossover using techniques like Feshbach associ­a­tion in a large optical box trap and precise molec­u­lar inter­ac­tion control via combined microwave fields. Addition­ally, the goal is to create, observe, and manip­u­late MZMs by stirring the super­fluid to form vortices where MZMs could exist. Using optical tweez­ers, the vortices can be braided, enabling qubit gate opera­tions. Absorp­tion imaging will provide readout, poten­tially offer­ing defin­i­tive evidence for MZMs.