UltracoldTetramers · Optical formation of ground state ultracold tetratomic molecules

There is currently growing interest in forming ultracold polyatomic molecules. It is anticipated that their rich internal structure will provide powerful platforms for quantum information processing, precision measurements, studies in cold-controlled chemistry, and simulation of quantum many-body systems. In a recent ground-breaking experiment, weakly bound ultracold tetratomic molecules (“tetramers”) have been realized from pairs of ultracold alkali-metal diatoms using external fields [Nature, 626, 283 (2024)]. It also opened a new question on how such weakly bound tetramers can be transferred to their absolute ground state. The main challenge is to mitigate their collisional loss from experimental traps which is expected to be very high due to an immense number of internal degrees of freedom. In this Action, I will propose novel theoretical methods to transfer weakly bound ultracold tetramers to deeply bound states in their ground electronic potential using lasers. To achieve this goal, I will combine two well-established methods for ultracold diatomic molecules: (a) Collisional shielding of molecules against inelastic and reactive loss, and (b) Stimulated Raman Adiabatic Passage (STIRAP) method for transferring weakly bound ultracold molecules to their ground vibronic state. I will implement the method (a) for molecules colliding in an excited electronic state required for STIRAP. I will develop a new method (b) which will enable the creation of deeply bound ultracold tetramers.Successful implementation of this project will create a new indirect method of creating ultracold polyatomic molecules in deeply bound states. The proposed method is near-universal and can be applied to a wide range of molecules. Stable gases of such molecules will allow the creation of a new type of Bose-Einstein Condensate made of polyatomic molecules. This Action will enable me to expand my skillsets in cutting-edge ultracold research and will help to launch my independent career.