Speaker
Description
Cold molecules exhibit significant potential in many applications, including precision measurement, quantum metrology, and fundamental physics. Although a few specific types of molecules have been successfully laser-cooled by selecting electronic transitions with appropriate Franck-Condon factors, laser deceleration of general molecules still poses significant challenges. In order to explore the possibility of molecular deceleration, we propose a method via the vibrational coherent bichromatic force (V-BCF). The bichromatic force, utilizing a pair of well-controlled counterpropagating laser beams with respect to frequency and phase, produces a significant coherent force related to the momentum transfer process of stimulated radiation rather than spontaneous radiation, which relies on the inherent characteristics of the system. Compared with the conventional BCF that operates through molecular electronic states, the V-BCF scheme based on the fundamental vibrational transitions benefits from the ultralow relaxation rate, undergoing continuous absorption-stimulated radiation cycles without interruptions caused by spontaneous radiation. This continuity in the Bloch evolution means a significant net momentum transfer that enables the molecular deceleration. Take the vibrational transition R(0) (00011)–(000021) of $^{13}CO_{2}$ as a demonstration, we calculated the V-BCF and found a time-averaged maximum deceleration of $-1.46×10^5~m/s^2$ with the velocity capture range $Δv_c$ of about $130~m/s$. The result indicated that it was possible to decelerate $^{13}CO_{2}$ with V-BCF. Based on the study we propose that molecules, as long as they have a sufficiently large fundamental vibration transition dipole moment or sufficiently large laser power at the fundamental vibrational band, can be decelerated by the V-BCF scheme. The universal method to decelerate and manipulate the molecule provides an opportunity for precision spectroscopy of molecules and more applications where slow and cold molecules are needed.