Abstract This study systematically investigates the spin relaxation characteristics of alkali‐metal atoms in spin‐exchange relaxation‐free (SERF) co‐magnetometers, focusing on mitigating the radiation trapping to reduce the alkali‐metal spin relaxation rate. Radiation trapping is one of the dominant mechanisms exacerbating spin relaxation in alkali‐metal atoms and is conventionally suppressed by introducing nitrogen () as a quenching agent. However, experiments reveal that the typical concentration in current SERF co‐magnetometers is insufficient to effectively suppress radiation trapping. By increasing the quenching gas concentration, additional attenuation of the radiation trapping effect is achieved. Meanwhile, to address the enhanced spin‐exchange collision relaxation arising from higher concentration, the operating temperature is adjusted to increase the alkali‐metal atom number density, thereby effectively curtailing this adverse effect. Experimental results demonstrate that the synergistic optimization of concentration and temperature reduces alkali‐metal spin relaxation by approximately 55% and decreases the noise power spectral density of the co‐magnetometer by 48.5% at 1 Hz. These findings confirm the effectiveness of this approach in improving the accuracy and sensitivity of SERF co‐magnetometers.Abstract This study systematically investigates the spin relaxation characteristics of alkali‐metal atoms in spin‐exchange relaxation‐free (SERF) co‐magnetometers, focusing on mitigating the radiation trapping to reduce the alkali‐metal spin relaxation rate. Radiation trapping is one of the dominant mechanisms exacerbating spin relaxation in alkali‐metal atoms and is conventionally suppressed by introducing nitrogen () as a quenching agent. However, experiments reveal that the typical concentration in current SERF co‐magnetometers is insufficient to effectively suppress radiation trapping. By increasing the quenching gas concentration, additional attenuation of the radiation trapping effect is achieved. Meanwhile, to address the enhanced spin‐exchange collision relaxation arising from higher concentration, the operating temperature is adjusted to increase the alkali‐metal atom number density, thereby effectively curtailing this adverse effect. Experimental results demonstrate that the synergistic optimization of concentration and temperature reduces alkali‐metal spin relaxation by approximately 55% and decreases the noise power spectral density of the co‐magnetometer by 48.5% at 1 Hz. These findings confirm the effectiveness of this approach in improving the accuracy and sensitivity of SERF co‐magnetometers.

Advanced Quantum TechnologiesApr 8, 20254 citations

Measurement of charge exchange between Na and Ca+ in a hybrid trap

Jonathan M. Kwolek, D. S. Goodman, Benjamin Slayton +4 more

We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium ( ${\mathrm{Ca}}^{+}$ ) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and ${\mathrm{Ca}}^{+}$ are co-trapped, the reaction rate is measured by continuously quenching the reaction product ${\mathrm{Na}}^{+}$ from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reaction rates between $\text{Na}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}P]$ and ${\text{Ca}}^{+}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}D]$ at different collision energies. With the exception of the largest reaction-rate channel ( $\text{Na}[P]+{\text{Ca}}^{+}[D]$ ), our rates are consistent with the classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance channels.We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium (${\mathrm{Ca}}^{+}$) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and ${\mathrm{Ca}}^{+}$ are co-trapped, the reaction rate is measured by continuously quenching the reaction product ${\mathrm{Na}}^{+}$ from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reaction rates between $\text{Na}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}P]$ and ${\text{Ca}}^{+}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}D]$ at different collision energies. With the exception of the largest reaction-rate channel ($\text{Na}[P]+{\text{Ca}}^{+}[D]$), our rates are consistent with the classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance channels.

arXiv:1812.02810Physical Review AMay 24, 20198 citations

Linear-scale simulations of quench dynamics

Niaz Ali Khan, Wen Chen, Munsif Jan +1 more

arXiv:2311.09556Computer Physics CommunicationsFeb 13, 20246 citations

Comparison of Cluster Models in the Interpretation of Green Fluorescence Experiment Performed on 6 High Concentration Erbium-Doped Silica Fibres

Jacob L. Philepsen, Jes Broeng, Anders Bjarklev +3 more

We formulate a new and detailed 3-energy-level model for clustered Er3+-ions and use it in the interpretation of a green fluorescence experiment for characterizing energy transfer upconversion in clusters. We compare with the results obtained by use of an already existing model. Furthermore, comparison between 6 different fibres shows that for increasing Er3+-concentration, a larger fraction of the Er3+-ions become clustered, but the quenching through energy transfer upconversion on the other hand becomes slower, and quenching times for clustered Er3+-ions as long as several hundred μs are observed.We formulate a new and detailed 3-energy-level model for clustered Er3+-ions and use it in the interpretation of a green fluorescence experiment for characterizing energy transfer upconversion in clusters. We compare with the results obtained by use of an already existing model. Furthermore, comparison between 6 different fibres shows that for increasing Er3+-concentration, a larger fraction of the Er3+-ions become clustered, but the quenching through energy transfer upconversion on the other hand becomes slower, and quenching times for clustered Er3+-ions as long as several hundred μs are observed.

Jul 11, 19962 citations

We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium (

{\mathrm{Ca}}^{+}

) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and

{\mathrm{Ca}}^{+}

are co-trapped, the reaction rate is measured by continuously quenching the reaction product

{\mathrm{Na}}^{+}

from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reaction rates between

\text{Na}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}P]

and

{\text{Ca}}^{+}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}D]

at different collision energies. With the exception of the largest reaction-rate channel (

\text{Na}[P]+{\text{Ca}}^{+}[D]

), our rates are consistent with the classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance channels.