Atomic, Molecular, Optical Science

Do homonuclear diatomic molecules have a permanent dipole moment?

Our atmosphere consists mainly of homonuclear diatomic molecules (N₂ and O₂). However, the molecules that affected the Earth's temperature are only present in a much smaller concentration. The reason is that molecules like CO₂ have a permanent dipole moment, which allows them to absorb and emit infrared radiation efficiently. In contrast, homonuclear diatomic molecules are transparent to this radiation due to their symmetry and lack of a permanent dipole moment (within the Born-Oppenheimer approximation). 

In this talk, a new study will be presented on the internal dynamics of hot diatomic molecules of Ag₂^- and Cu₂^-. The molecules were produced in a hot ion source, stored in an electrostatic ion beam trap, and a CW laser was used to photo-detach the molecules while in the trap. A special electron spectrometer, built inside the trap, was used to monitor the photoelectron spectra for up to several seconds after molecular production. Internal molecular dynamics were observed, suggesting spontaneous cooling due to dipole transitions.

The above finding supports a new speculation about primordial star formation. This speculation will also be discussed.

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There will be no Seminar

Unlocking New Capabilities for Quantum Computation and Simulation with Neutral Atom Arrays

Neutral atom arrays have become a frontrunner in the race for utility scale quantum computation [1], building on their reconfigurability [2], scalability [3] and high fidelity for all operations [4] - idling, detection, single- and two-qubit gates. They have also produced large scale quantum simulation of complex many-body systems [5]. However, they still suffer key bottlenecks that constrain their operational speed, their deep quantum circuit implementation and the range of physical models thye are able to simulate. In this talk, I will show how my recent work can bend these constraints and sometimes completely break them. I will present my work on accelerated detection of the atoms via high-lying energy states (Rydberg states) [6] and introduce novel protocols for reconfigurable multi-qubit gates [7], promoting improved circuit implementation speed and error rates. I will show how arbitrary spin-spin interaction models can be implemented in atom arrays through Floquet engineering [8], extending their ability to simulate many important quantum magnetism models. I will then update on our current progress in building a continuously operating neutral atom quantum processor, which mitigates the negative influences of atom loss, and present a new scheme we developed to operate atom array systems for this purpose [9]. Lastly, I will touch on the final frontier - how to increase system size to a utility scale number of qubits - and provide my own solution to it: free electron quantum interconnects between neutral atom quantum processing modules.  

References

[1] D. Bluvstein et al, Nature 649, 39–46 (2026)

[2] D. Bluvstein et al, Nature 604, 451–456 (2022)

[3] H. J. Manetsch et al, Nature 647, 60–67 (2025)

[4] D. Bluvstein et al, Nature 626, 58–65 (2024)

[5] A. Browaeys & T. Lahaye, Nat. Phys. 16, 132–142 (2020)

[6] T. Sumarac*, E. Qiu*, S. Tsesses* et al, arXiv

[7] J. Bender*, S. Tsesses* et al, in preparation

[8] N. Nishad et al, Phys. Rev. A 108, 053318 (2023)

[9] E. Qiu*, T. Sumarac*, P. Niu* et al, arXiv:2509.12124