arXiv subjects

Geoffrey Zheng

Publications and source records attributed to Geoffrey Zheng.

4 recordsLinked to original sources

arXiv2026

Non-destructive cavity readout of molecules for precision measurements

We propose a non-destructive method to measure the population of molecules in a selected rotational-hyperfine state by coupling them to a high-finesse optical cavity. In contrast to traditional techniques, our approach enables fast (less than 1 ms) repeated measurements with reduced heating and losses, and with precision below the standard quantum limit. The method is particularly advantageous for radioactive molecules, systems of high interest for symmetry violation searches, for which production and sample size are limited, and repeated interrogation is essential for improved sensitivity.

physics.atom-ph↗

arXiv2026

Parity non-conservation in isotope chain of tin

We calculate parity non-conservation (PNC) amplitudes for all magnetic-dipole (M1) transitions within the ground $5p^2$ configuration of Sn, including the standard model interaction and contribution of a hypothetical additional $Z'$-boson. Among the transitions considered, the $^1$S$_0$-$^3$P$_1$ transition has the largest PNC amplitude and appears to be the most promising candidate for an experiment. We also discuss a measurement method capable of achieving unprecedentedly high precision in a measurement of PNC in this transition. We argue that the most robust test should be based on ratios of PNC amplitudes for different isotopes, since the atomic-structure factor largely cancels in such ratios. We study the effect of the neutron skin on these isotope ratios using available nuclear data for Sn and show that the uncertainty associated with the neutron skin can be reduced to the $10^{-4}$ level relative to the isotopic variation of the PNC effect. Our results indicate that PNC measurements along a chain of Sn isotopes offer a realistic and sensitive probe of new physics.

physics.atom-ph↗

arXiv2025

Simulated Laser Cooling and Magneto-Optical Trapping of Group IV Atoms

We present a scheme for laser cooling and magneto-optical trapping of the Group IV (a.k.a. Group 14 or tetrel) atoms silicon (Si), germanium (Ge), tin (Sn), and lead (Pb). These elements each possess a strong Type-II transition ($J \rightarrow J' = J-1$) between the metastable $s^2p^2 \,^3P_1$ state and the excited $s^2ps'\, ^3P_0^o$ state at an accessible laser wavelength, making them amenable to laser cooling and trapping. We focus on the application of this scheme to Sn, which has several features that make it attractive for precision measurement applications. We perform numerical simulations of atomic beam slowing, capture into a magneto-optical trap (MOT), and subsequent sub-Doppler cooling and compression in a blue-detuned MOT of Sn atoms. We also discuss a realistic experimental setup for realizing a high phase-space density sample of Sn atoms.

physics.atom-ph↗

arXiv2023

High density loading and collisional loss of laser cooled molecules in an optical trap

We report optical trapping of laser-cooled molecules at sufficient density to observe molecule-molecule collisions for the first time in a bulk gas. SrF molecules from a red-detuned magneto-optical trap (MOT) are compressed and cooled in a blue-detuned MOT. Roughly 30% of these molecules are loaded into an optical dipole trap with peak number density $n_0 \approx 3\times 10^{10} \text{ cm}^{-3}$ and temperature $T\approx40$ $μ$K. We observe two-body loss with rate coefficient $β= 2.7^{+1.2}_{-0.8}\times 10^{-10} \text{ cm}^3 \text{ s}^{-1}$. Achieving this density and temperature opens a path to evaporative cooling towards quantum degeneracy of laser-cooled molecules.

physics.atom-ph↗