We report on the preparation of a quantum degenerate mixture of $^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}$ molecules and $^{40}\mathrm{K}$ atoms. A deeply degenerate atomic mixture of $^{23}\mathrm{Na}$ and $^{40}\mathrm{K}$ atoms with a large number ratio (${N}_{F}/{N}_{B}\ensuremath{\approx}6$) is prepared in a large-volume optical dipole trap. About $3.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}$ ground-state molecules are created through magnetoassociation followed by stimulated Raman adiabatic passage. The pure molecular gas is in the moderately degenerate regime. In the atom-molecule mixture, the elastic collisions provide a thermalization mechanism for the molecules. The calculated thermalization time constant is smaller than the lifetime of the molecules in the atom-molecule mixture. This indicates that the molecules may reach thermal equilibrium due to elastic atom-molecule collisions before notable losses take place. In a few tens of milliseconds, the degeneracy of the molecules is maintained. This time interval is long enough for the study of strongly interacting atom-molecule mixtures and the production of ultracold triatomic molecular gases.We report on the preparation of a quantum degenerate mixture of $^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}$ molecules and $^{40}\mathrm{K}$ atoms. A deeply degenerate atomic mixture of $^{23}\mathrm{Na}$ and $^{40}\mathrm{K}$ atoms with a large number ratio (${N}_{F}/{N}_{B}\ensuremath{\approx}6$) is prepared in a large-volume optical dipole trap. About $3.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}$ ground-state molecules are created through magnetoassociation followed by stimulated Raman adiabatic passage. The pure molecular gas is in the moderately degenerate regime. In the atom-molecule mixture, the elastic collisions provide a thermalization mechanism for the molecules. The calculated thermalization time constant is smaller than the lifetime of the molecules in the atom-molecule mixture. This indicates that the molecules may reach thermal equilibrium due to elastic atom-molecule collisions before notable losses take place. In a few tens of milliseconds, the degeneracy of the molecules is maintained. This time interval is long enough for the study of strongly interacting atom-molecule mixtures and the production of ultracold triatomic molecular gases.

arXiv:2208.09620Physical Review AJan 17, 202315 citations

The Quantum Mechanics of Atoms and Molecules

J. E. Lennard-Jones

Journal of the London Mathematical SocietyOct 1, 19319 citations

Coherent Creation of Single Molecules from Single Atoms

Yichao Yu

Molecules, with their rich spectrum of internal states as well as strong and tunable dipolar interactions, are promising candidates for a broad range of experiments including quantum information, quantum chemistry, precision measurement and probing physics beyond the Standard Model, and quantum simulation of interacting many-body systems. At the same time, the complexity that made them attractive also poses a significant challenge to achieve a high level of quantum control that is required in many of their potential applications. Multiple approaches are being pursued for full quantum control of molecules including association of atomic gases and direct cooling of molecules, yet it remains challenging to control molecules at single particle level due to the difficulty in tuning the atom-atom interaction and laser cooling of molecules. In this thesis, we achieved full control on a single weakly bound ground state molecule created by coherent optical association from single atoms. We first discuss the trapping and imaging of the atoms in the optical tweezer and the cooling into a single quantum state in order to achieve the quantum control of atoms. Combining this control with the resolution and flexibility of tweezers. we developed a versatile platform to study interactions between single atoms and properties of single molecules, using precise optical spectroscopy on pairs of atoms in the tweezer. Based on these studies, we proposed a promising pathway for coherent all-optical creation of molecules and experimentally demonstrated full control on the molecule including all degrees of freedom.Molecules, with their rich spectrum of internal states as well as strong and tunable dipolar interactions, are promising candidates for a broad range of experiments including quantum information, quantum chemistry, precision measurement and probing physics beyond the Standard Model, and quantum simulation of interacting many-body systems. At the same time, the complexity that made them attractive also poses a significant challenge to achieve a high level of quantum control that is required in many of their potential applications. Multiple approaches are being pursued for full quantum control of molecules including association of atomic gases and direct cooling of molecules, yet it remains challenging to control molecules at single particle level due to the difficulty in tuning the atom-atom interaction and laser cooling of molecules. In this thesis, we achieved full control on a single weakly bound ground state molecule created by coherent optical association from single atoms. We first discuss the trapping and imaging of the atoms in the optical tweezer and the cooling into a single quantum state in order to achieve the quantum control of atoms. Combining this control with the resolution and flexibility of tweezers. we developed a versatile platform to study interactions between single atoms and properties of single molecules, using precise optical spectroscopy on pairs of atoms in the tweezer. Based on these studies, we proposed a promising pathway for coherent all-optical creation of molecules and experimentally demonstrated full control on the molecule including all degrees of freedom.

Jan 1, 20210 citations

Atoms and Molecules as Bound Quantum Systems

K. N. Joshipura, Nigel John Mason

Cambridge University Press eBooksDec 21, 20180 citations

Quantum dynamics and statistical properties of atom-molecule Bose-Einstein condensates

Guangri Jin, Chul Koo Kim, Kyun Nahm

Based on a two-mode boson model, we study nonclassical properties of the atom-molecule Bose-Einstein condensate. The effects of nonlinear collisions on the dynamics of the molecular formation is studied both in classical and quantum treatments. We find that the conversion from atoms to molecules can be suppressed strongly due to nonlinearity induced localization of the atomic population. In addition, we study statistical properties of the atom-molecule condensed system by calculating the intensity correlation functions numerically. We find that the effect of nonlinearity leads to the appearance of superchaotic molecular pulses, while maintaining the atomic field sub-Poissonian. The joint quantum statistical properties of the atoms and the molecules always show antibunching.Based on a two-mode boson model, we study nonclassical properties of the atom-molecule Bose-Einstein condensate. The effects of nonlinear collisions on the dynamics of the molecular formation is studied both in classical and quantum treatments. We find that the conversion from atoms to molecules can be suppressed strongly due to nonlinearity induced localization of the atomic population. In addition, we study statistical properties of the atom-molecule condensed system by calculating the intensity correlation functions numerically. We find that the effect of nonlinearity leads to the appearance of superchaotic molecular pulses, while maintaining the atomic field sub-Poissonian. The joint quantum statistical properties of the atoms and the molecules always show antibunching.

arXiv:cond-mat/0504381Physical Review AOct 26, 200520 citations

We report on the preparation of a quantum degenerate mixture of

^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}

molecules and

^{40}\mathrm{K}

atoms. A deeply degenerate atomic mixture of

^{23}\mathrm{Na}

and

^{40}\mathrm{K}

atoms with a large number ratio (${N}_{F}/{N}_{B}\ensuremath{\approx}6$) is prepared in a large-volume optical dipole trap. About $3.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.16em}{0ex}}^{23}\mathrm{Na}\phantom{\rule{0.16em}{0ex}}^{40}\mathrm{K}$ ground-state molecules are created through magnetoassociation followed by stimulated Raman adiabatic passage. The pure molecular gas is in the moderately degenerate regime. In the atom-molecule mixture, the elastic collisions provide a thermalization mechanism for the molecules. The calculated thermalization time constant is smaller than the lifetime of the molecules in the atom-molecule mixture. This indicates that the molecules may reach thermal equilibrium due to elastic atom-molecule collisions before notable losses take place. In a few tens of milliseconds, the degeneracy of the molecules is maintained. This time interval is long enough for the study of strongly interacting atom-molecule mixtures and the production of ultracold triatomic molecular gases.