Abstract: Over the past decade, advances in atomic, molecular, and optical (AMO) physics techniques enabled the cooling of simple molecules down to the ultracold regime (< 1 mK), allowing unprecedented control over their quantum states. This opened a host of new opportunities in quantum information, precision measurement, and controlled chemistry. I will discuss two experiments on precisely probing and controlling inter- and intramolecular dynamics at ultralow temperatures, respectively. The first experiment studies the exchange reaction between potassium-rubidium (KRb) molecules initiated at a temperature of 500 nK, in which we understand and control the reaction dynamics on a state-to-state level, and reveal surprising properties of chemistry at ultralow temperatures [1]. In the second experiment, we developed a general protocol, based on the quantum-logic technique [2,3], to track the quantum jumps within a single molecular ion under an external perturbation. We applied this technique to control a CaH+ ion in a target rotational state against the effects of depopulation due to black-body radiation from the surrounding environment. This substantially increases the duty-cycle of experiments that require the molecular ion to be initialized in a pure quantum state, which we leverage towards our ongoing effort of performing vibrational overtone spectroscopy of molecular ions with below 10^-14 uncertainty.
[1] Y. Liu & K.-K. Ni Annual review of physical chemistry, 73, 73-96 (2022).
[2] P. O. Schmidt et al., Science, 309(5735), 749-752 (2005).
[3] C.-W. Chou et al., Nature 545, 203 (2017)
Note: Yu Liu is one of the new quantum hires in UMD Chemistry.