Abstract Improved optical control of molecular quantum states promises new applications including chemistry in the quantum regime, precision tests of fundamental physics, and quantum information processing. While much work has sought to prepare ground state molecules, excited states are also of interest. Here, we demonstrate a broadband optical approach to pump trapped SiO+ molecules into pure super rotor ensembles maintained for many minutes. Super rotor ensembles pumped up to rotational state N = 67, corresponding to the peak of a 9400 K distribution, had a narrow N spread comparable to that of a few-kelvin sample, and were used for spectroscopy of the previously unobserved C2Π state. Significant centrifugal distortion of super rotors pumped up to N = 230 allowed probing electronic structure of SiO+ stretched far from its equilibrium bond length.Abstract Improved optical control of molecular quantum states promises new applications including chemistry in the quantum regime, precision tests of fundamental physics, and quantum information processing. While much work has sought to prepare ground state molecules, excited states are also of interest. Here, we demonstrate a broadband optical approach to pump trapped SiO+ molecules into pure super rotor ensembles maintained for many minutes. Super rotor ensembles pumped up to rotational state N = 67, corresponding to the peak of a 9400 K distribution, had a narrow N spread comparable to that of a few-kelvin sample, and were used for spectroscopy of the previously unobserved C2Π state. Significant centrifugal distortion of super rotors pumped up to N = 230 allowed probing electronic structure of SiO+ stretched far from its equilibrium bond length.

arXiv:2008.01904Nature CommunicationsApr 13, 202113 citations

Cooling and Trapping of Molecules

Jesús Pérez‐Ríos

Springer eBooksJan 1, 20201 citation

Cooling and trapping of molecules in highly excited rotational states

Robert C. Forrey

Collisional relaxation of highly rotating hydrogen molecules is investigated as a function of energy. Calculations demonstrate that inelastic collisions are dramatically suppressed for specific rotational levels of the molecule as the energy is lowered due to the closing of quasiresonant rotation-vibration channels. It is predicted that a ${}^{3}\mathrm{He}$ buffer gas may be used to load these highly excited molecules into a trap without a significant loss of population. It is further predicted that evaporative cooling may be used to cool the ``super rotors'' to even lower temperatures.Collisional relaxation of highly rotating hydrogen molecules is investigated as a function of energy. Calculations demonstrate that inelastic collisions are dramatically suppressed for specific rotational levels of the molecule as the energy is lowered due to the closing of quasiresonant rotation-vibration channels. It is predicted that a ${}^{3}\mathrm{He}$ buffer gas may be used to load these highly excited molecules into a trap without a significant loss of population. It is further predicted that evaporative cooling may be used to cool the ``super rotors'' to even lower temperatures.

Physical Review AApr 18, 200143 citations

Collisional cooling and trapping of molecules

Kevin E. Strecker, David W. Chandler

APSJun 1, 20070 citations

Sympathetic rotational cooling of large trapped molecular ions

M. Leibscher, Blech, Alexander, Christiane P. Koch

We suggest a protocol for the sympathetic cooling of a molecular asymmetric top rotor co-trapped with laser-cooled atomic ions, based on resonant coupling between the molecular ion's electric dipole moment and a common normal mode of the trapped particles. By combining sympathetic sideband laser cooling with coherent microwave excitation, we demonstrate the efficient depopulation of arbitrary rotational subspaces and the ability to cool an incoherent distribution of rotational states into a single, well-defined quantum state. This capability opens the door to exploiting the rotational Hilbert space for applications in quantum information processing and high-precision spectroscopy.We suggest a protocol for the sympathetic cooling of a molecular asymmetric top rotor co-trapped with laser-cooled atomic ions, based on resonant coupling between the molecular ion's electric dipole moment and a common normal mode of the trapped particles. By combining sympathetic sideband laser cooling with coherent microwave excitation, we demonstrate the efficient depopulation of arbitrary rotational subspaces and the ability to cool an incoherent distribution of rotational states into a single, well-defined quantum state. This capability opens the door to exploiting the rotational Hilbert space for applications in quantum information processing and high-precision spectroscopy.

arXiv:2506.20846Jun 25, 20250 citations

{}^{3}\mathrm{He}

buffer gas may be used to load these highly excited molecules into a trap without a significant loss of population. It is further predicted that evaporative cooling may be used to cool the ``super rotors'' to even lower temperatures.