Ab initiostudy of laser cooling of AlF+and AlCl+molecular ions

AbstractEfficient cooling of trapped charged particles is essential to many fundamental physics experiments1,2, to high-precision metrology3,4 and to quantum technology5,6. Until now, sympathetic cooling has required close-range Coulomb interactions7,8, but there has been a sustained desire to bring laser-cooling techniques to particles in macroscopically separated traps5,9,10, extending quantum control techniques to previously inaccessible particles such as highly charged ions, molecular ions and antimatter. Here we demonstrate sympathetic cooling of a single proton using laser-cooled Be+ ions in spatially separated Penning traps. The traps are connected by a superconducting LC circuit that enables energy exchange over a distance of 9 cm. We also demonstrate the cooling of a resonant mode of a macroscopic LC circuit with laser-cooled ions and sympathetic cooling of an individually trapped proton, reaching temperatures far below the environmental temperature. Notably, as this technique uses only image–current interactions, it can be easily applied to an experiment with antiprotons1, facilitating improved precision in matter–antimatter comparisons11 and dark matter searches12,13.

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On the Feasibility of Rovibrational Laser Cooling of Radioactive RaF+ and RaH+ Cations

Atoms ◽

10.3390/atoms9040101 ◽

2021 ◽

Vol 9 (4) ◽

pp. 101

Author(s):

Timur A. Isaev ◽

Shane G. Wilkins ◽

Michail Athanasakis-Kaklamanakis

Keyword(s):

Laser Cooling ◽

Ground State ◽

Ion Beam ◽

Molecular Ions ◽

Buffer Gas ◽

Neutral System ◽

Internal Temperature ◽

Buffer Gas Cooling ◽

Transition Energies ◽

Direct Laser

Polar radioactive molecules have been suggested to be exceptionally sensitive systems in the search for signatures of symmetry-violating effects in their structure. Radium monofluoride (RaF) possesses an especially attractive electronic structure for such searches, as the diagonality of its Franck-Condon matrix enables the implementation of direct laser cooling for precision experiments. To maximize the sensitivity of experiments with short-lived RaF isotopologues, the molecular beam needs to be cooled to the rovibrational ground state. Due to the high kinetic energies and internal temperature of extracted beams at radioactive ion beam (RIB) facilities, in-flight rovibrational cooling would be restricted by a limited interaction timescale. Instead, cooling techniques implemented on ions trapped within a radiofrequency quadrupole cooler-buncher can be highly efficient due to the much longer interaction times (up to seconds). In this work, the feasibility of rovibrationally cooling trapped RaF+ and RaH+ cations with repeated laser excitation is investigated. Due to the highly diagonal nature between the ionic ground state and states in the neutral system, any reduction of the internal temperature of the molecular ions would largely persist through charge-exchange without requiring the use of cryogenic buffer gas cooling. Quasirelativistic X2C and scalar-relativistic ECP calculations were performed to calculate the transition energies to excited electronic states and to study the nature of chemical bonding for both RaF+ and RaH+. The results indicate that optical manipulation of the rovibrational distribution of trapped RaF+ and RaH+ is unfeasible due to the high electronic transition energies, which lie beyond the capabilities of modern laser technology. However, more detailed calculations of the structure of RaH+ might reveal possible laser-cooling pathways.

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Blackbody-Radiation–Assisted Laser Cooling of Molecular Ions

Physical Review Letters ◽

10.1103/physrevlett.89.173003 ◽

2002 ◽

Vol 89 (17) ◽

Cited By ~ 43

Author(s):

I. S. Vogelius ◽

L. B. Madsen ◽

M. Drewsen

Keyword(s):

Laser Cooling ◽

Molecular Ions ◽

Blackbody Radiation

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LC circuit mediated sympathetic cooling of a proton via image currents

10.21203/rs.3.rs-351267/v1 ◽

2021 ◽

Author(s):

Matthew Bohman ◽

Valentin Grunhofer ◽

Christian Smorra ◽

Markus Wiesinger ◽

Christian Will ◽

...

Keyword(s):

Laser Cooling ◽

Quantum Control ◽

Penning Trap ◽

Resonant Mode ◽

Molecular Ions ◽

Coulomb Interactions ◽

Sympathetic Cooling ◽

Control Techniques ◽

Environment Temperature ◽

Lc Circuit

Abstract Efficient cooling of trapped charged particles is essential in many fundamental physics experiments, for high-precision metrology, and for quantum technology. Until now, ion-ion coupling for sympathetic cooling or quantum state control has been limited to ion species with accessible optical transitions or has required close-range Coulomb interactions. To overcome this limitation and further develop scalable quantum control techniques, there has been a sustained desire to extend laser-cooling techniques to particles in macroscopically separated traps, opening quantum control techniques to previously inaccessible particles such as highly charged ions, molecular ions, and antimatter particles. Here, we demonstrate sympathetic cooling of a single proton by laser cooled Be+ ions stored in a spatially separated Penning trap. The two traps are connected by a superconducting LC circuit that enables energy exchange over a distance of 9 cm. We simultaneously demonstrate the cooling of a resonant mode of a macroscopic LC circuit with laser-cooled ions and sympathetic cooling of an individually trapped proton, reaching temperatures far below the environment temperature. Importantly, as this technique does not rely on the direct Coulomb interaction but rather on image-current interactions, it can be easily applied to an experiment with antiprotons, facilitating improved precision in matter-antimatter comparisons and dark matter searches.

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