Speaker
Description
Trapped atomic ions offer long lifetimes and high-fidelity operations [1]. However, their relatively simple internal structure can pose a limitation for scalability. In contrast, diatomic molecules possess a rich internal structure of rotations, vibrations and hyperfine levels, allowing each molecule to store more information than a single atomic ion [2]. Furthermore, the permanent electric dipole moments of polar molecules produce tuneable long-range dipole-dipole interactions.
These properties make trapped molecular ions an attractive platform for quantum computing, simulation and fundamental science. Microwave fields allow coherent manipulation of rotational states, providing a means to encode quantum information and implement gate operations [3,4,5]. Additionally, the dipolar nature of molecules enables entangling operations mediated by electric dipole-dipole interactions [6]. By addressing rotational states with microwave fields, it is possible to induce state-dependent interactions between molecules and realize entangling gates, such as iSWAP, without relying on shared motional modes [3]. This approach offers a potential route towards a scalable architecture that circumvents some limitations associate motional mode-based gates in atomic ion systems.
Beyond quantum simulations, molecules’ high sensitivity to fundamental constants facilitates probing fundamental physics in the laboratory. [7]. A trapped molecular ion system shows potential to combine the strengths of both atomic ion traps and neutral molecules. In this work, we present path towards producing a hybrid atomic-molecular ion trap for Sr+ and SrF+.
A key component for this work is the development of a reliable and controllable source of SrF radicals, which can be selectively photoionized. For this purpose, we are designing a compact supersonic beam source of SrF radicals. Using the X->A transition at 663nm, we aim to selectively excite a single quantum state of the molecule and drive it to the continuum, creating a high-flux source of molecular ions.
We cover the development of a custom laser system for laser-induced-fluorescence detection of SrF. This system will characterize the performance of our supersonic source by measuring the velocity distribution via time-of-flight imaging. Additionally, we will use the laser for the first stage in a two-photon ionization process which will enable future measurements of the photoionization threshold of SrF. These developments establish a foundation for controlled production and trapping of molecular ions, enabling future studies of dipole-modulated quantum gates, and quantum simulations with hybrid ion systems.
Citations:
[1] Smith, Molly et al. ‘Single-Qubit Gates with Errors at the 10 − 7 Level’. Physical Review Letters (2025)
[2] Rahul Sawant et al ‘Ultracold polar molecules as qudits’ New J. Phys. (2020)
[3] Ni, Kang-Kuen, et al. ‘Dipolar Exchange Quantum Logic Gate with Polar Molecules’. Chemical Science (2018)
[4] Hepworth, Tom, et al. ‘Long-Lived Multilevel Coherences and Spin-1 Dynamics Encoded in the Rotational States of Ultracold Molecules’. Nature Communications (2025)
[5] Jacob Blackmore et al ‘Ultracold molecules for quantum simulation: rotational coherences in CaF and RbCs’ Quantum Sci. Technol. (2019)
[6] Ruttley, Daniel, et al. ‘Long-Lived Entanglement of Molecules in Magic-Wavelength Optical Tweezers’. Nature (2025)
[7] Roussy, Tanya , et al. ‘An Improved Bound on the Electron’s Electric Dipole Moment’. Science (2023)
| Academic level | PhD student |
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