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Cornell University

Katz Lab

Setting atoms & ions in |motion>

Experimental Quantum Chemistry

 

Inelastic processes and chemical reactions have long captured great scientific and applicable interest. When two atoms are brought into close proximity, they can change their physical state and convert their internal energy into an increase or decrease in their kinetic energy. Traditionally, these processes are studied by measuring variations in average thermodynamic properties such as the temperature, energy and pressure of macroscopic samples comprising many atoms.

At the microscopic scale, the dynamics and outcome of such processes are governed by the rules of quantum mechanics. Short-range chemical forces typically produce many-body correlations in the electronic state of the atoms that comprise a molecular complex. As modest molecular complexes typically consist of tens to hundreds of electrons, and as the necessary computing power for an exact ab initio computation scales exponentially with the number of electrons, accurate calculation of a single collision outcome remains a great computational challenge. Consequently, accurate theoretical modelling often requires an experimental calibration of several free parameters.

Hybrid systems of laser-cooled trapped ions and ultracold neutral atoms offer pristine experimental tools for the study of collisions of a single ion–atom pair. These systems enable us to explore cold collisions as ions can be laser cooled near their motional ground state and atoms to temperatures below the millikelvin range and with single atom resolution. 
Atom-Ion setup. a. A cloud of neutral 87Rb atoms is laser cooled and loaded into an off-resonant optical dipole trap. A pair of ions is loaded in a linear Paul trap and cooled to near the ground state. The dilute atomic cloud is optically shuttled across the ions in the trap at velocity va, and during its passage, a spiraling collision between one atom in the cloud and one of the ions can occur. MOT, magneto-optical trap. b, Absorption imaging of the atomic cloud in the top chamber. c, Fluorescence imaging of a two-ion crystal composed of a logic ion (88Sr+) and a chemistry ion (86Sr+), which is always dark. The two orderings of the two-ion crystal are shown to exemplify the presence of the dark ion. See Nature Physics 18 533-537 (2022).

Selected Publications

  • “Quantum logic detection of collisions between single atom–ion pairs“. Katz, Pinkas, Akerman, Ozeri. Nature Physics 18 533-537 (2022).
  • “Trap-assisted formation of atom–ion bound states”, Pinkas, Katz, Wengrowicz, Akerman, Ozeri. Nature Physics 19 1573-1578 (2023).
  • “Quantum suppression of cold reactions far from the quantum regime“. Katz, Pinkas, Akerman, Ozeri. arXiv:2208.07725 (2022).