Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Laser cooling, optical trapping and Zeeman-Sisyphus deceleration of heavy polyatomic molecules for probing physics beyond the Standard Model

Hiromitsu Sawaoka

Published Jan 1, 2025• 0 citations
OpenAlex

Abstract

Ultracold polyatomic molecules containing heavy nuclei, such as SrOH and YbOH, are sensitive to T- symmetry violating and P-symmetry violating physics beyond the Standard Model through the electron’s electric dipole moment. Furthermore, SrOH is sensitive to ultralight Dark Matter through measuring time variations of fundamental constants. However, in order to make full use of these molecules, they need to be cooled to ultracold temperatures and held in optical traps. We have realized a magneto-optical trap (MOT) of SrOH and used this as the essential element to achieve optical trap- ping in the microKelvin temperature regime. We observed MOT lifetimes approaching 200 ms with temperatures ∼ 1 mK and observed damped oscillations in the MOT. We further cooled the SrOH molecules to ∼ 40 μ K using Λ-enhanced gray molasses, and compressed the cloud to about 100 μm size using the conveyor belt MOT technique. Using this ultracold dense cloud of SrOH, we loaded an optical dipole trap (ODT), with a molecular lifetime of 1.2(1) seconds. In separate experiments with YbOH, which is heavier than SrOH, we demonstrated a novel deceleration method (Zeeman- Sisyphus deceleration) that can slow YbOH to under 20 m/s with only a few photons scattered utilizing high magnetic fields up to 2.5 T. By driving spin-flip transitions at the maxima and minima of the magnetic fields, slowing was achieved, which is a critical first step toward loading of a MOT for this species. We addressed the challenges associated with driving spin-flip transitions in molecules that have molecular perturbations among the electronic excited states and developed an understanding of the physics of such systems that is applicable to a wide range of molecules.

Related papers

Improved Optical Trapping of SrOH to Probe Ultralight Dark Matter

Abdullah Nasir

Polyatomic molecules are promising platforms for conducting precision measurements to probe the Standard Model, owing to their unique degrees of freedom including vibrations and rotations. In particular, ultracold SrOH has sensitivity to the variation of the proton to electron mass ratio $\mu$ and subsequently to scalar ultralight dark matter (UDM) fields. We discuss the laser slowing, sub-Doppler cooling, and trapping of SrOH and present an order of magnitude improved trap number through the use of transverse cooling of the molecular beam resulting in $\sim$$10^4$ optically trapped molecules. This would allow for a two order of magnitude improvement on the current best sensitivities to UDM over four decades of mass. Probing $\mu$-variation is not only important for UDM studies, but has more general implications for a variety of fundamental physics searches. Additionally, this increase in trapped molecule number makes SrOH a viable candidate in the search for the electron's electric dipole moment ($e$EDM) for fundamental symmetry violations. These techniques are broadly applicable, and make cooling and trapping heavier and more complex molecules with greater sensitivity to fundamental physics more viable.

•Jan 1, 2026•0 citations

Magneto-Optical Trapping of a Heavy Polyatomic Molecule for Precision Measurement

Zack Lasner, Alexander Frenett, Hiromitsu Sawaoka +10 more

We report a magneto-optical trap of strontium monohydroxide (SrOH) containing 2000(600) molecules at a temperature of 1.2(3) mK. The lifetime is 91(9) ms, which is limited by decay to optically unaddressed vibrational states. This provides the foundation for future sub-Doppler cooling and optical trapping of SrOH, a polyatomic molecule suited for precision searches for physics beyond the standard model including new CP violating particles and ultralight dark matter. We also identify important features in this system that guide cooling and trapping of complex and heavy polyatomic molecules into the ultracold regime.

arXiv:2409.04948•Physical Review Letters•Feb 24, 2025•24 citations

Motional Control of Polyatomic Molecules for Precision Measurement

Alexander Frenett

Extending AMO techniques of motional control to heavy polyatomic molecules opens new possibilities for precision measurements of fundamental physics. Though various laser-cooling and deceleration techniques have been applied to diatomic molecules throughout the last decade, their application to more complex molecules has heretofore been focused on light species, leaving generalizability to heavy species an open question. To investigate the high-mass frontier, we here study how to extend motional control to heavy-atom-containing polyatomic molecules. First, we discuss Zeeman-Sisyphus deceleration of YbOH, which can be used to decelerate species capable of scattering only ~10s of photons. Then, we discuss radiative slowing and magneto-optical trapping of SrOH, techniques only extendable to species capable of scattering $\sim10^4$ photons. The last work focuses on spectroscopy of nonlinear molecules to assess the viability of extending techniques of motional control to more complex species. We find a dependence of both rotational and vibrational control on symmetry group, and identify a next-generation candidate for laser cooling. We end with a overview tying these projects together, and assessing the future of motional control along mass and complexity axes, including brief suggestions of how complementary methods to those studied here can further expand into the frontiers of molecular control.

•Jan 1, 2024•0 citations

Order of Magnitude Improved Optical Trapping of Molecules Through Transverse Cooling

Abdullah Nasir, Annika Lunstad, Mingda Li +5 more

We demonstrate a two-dimensional Sisyphus laser cooling method that increases the number of strontium monohydroxide (SrOH) molecules loaded into a magneto-optical trap by a factor of 12. Subsequent loading into an optical dipole trap (ODT) achieves $2.2 (3)\times10^4$ ultracold SrOH molecules with a peak density of $\sim2(1)\times10^{10}~\mathrm{cm^{-3}}$. The lifetime of molecules in the ODT is limited by two-body collisions characterized by a measured collision rate constant $β\sim 4\times10^{-10}~\mathrm{cm^3/s}$. The cooling method developed here is generally applicable to all known cases of direct molecular laser cooling, including symmetric and asymmetric top molecules. Increases in trapped molecule number will directly improve the search for ultralight dark matter, position polyatomic molecules as a platform for probing CP-violating new particles with masses $\gg$10 TeV, and facilitate a broad range of further research in quantum science.

arXiv:2607.16913•Jul 18, 2026•0 citations

Methods for Direct Laser Cooling of Polyatomic Molecules

Benjamin L. Augenbraun

Molecules controlled at the single-quantum-state level offer wide-ranging applications spanning many of the frontiers of modern physics. Within the past decade, simple diatomic molecules have been brought under full quantum control both via assembly from pre-cooled atoms and by direct laser cooling. Polyatomic molecules\footnote{Molecules that contain three or more atoms.} have attracted focus as novel quantum resources providing distinct advantages (and challenges) compared to both atoms and diatomic molecules. For example, nearly all polyatomic molecules have long-lived states that can be fully polarized at low applied electric fields. These and other features generic to polyatomic molecules can be applied to quantum simulation, quantum chemistry, and tests of fundamental physics beyond the Standard Model. While these structural features of polyatomic molecules are highly promising for applications, they complicate the process of bringing molecules under full quantum control. In this thesis, we describe a series of experimental and theoretical advances toward the production of ultracold complex polyatomic molecules. We demonstrate the first laser cooling of the polyatomic radical ytterbium monohydroxide (YbOH), a promising candidate to search for particles and interactions beyond the Standard Model of particle physics. We develop a novel deceleration technique (``Zeeman-Sisyphus deceleration") capable of slowing molecular beams to trappable velocities while scattering fewer than 10 optical photons. This deceleration method is demonstrated using CaOH molecules, a lighter analog of YbOH. In order to determine a viable pathway to full three-dimensional cooling and trapping of YbOH, we develop a spectroscopic technique to measure vibrational branching ratios with relative intensity sensitivity around 1 part in $10^5$, approximately two orders of magnitude beyond the previous state of the art. We also perform the first spectroscopic observations and characterizations of the related molecule ytterbium monomethoxide, YbOCH$_3$, a promising species to probe beyond-the-Standard-Model physics. In addition, we show theoretically that an entire class of asymmetric top molecules can be laser cooled using essentially the same techniques used for much simpler species. Measurements of the vibrational branching ratios for a few prototypical asymmetric to molecules (CaSH and CaNH$_2$) are presented to confirm these predictions.

•Jan 1, 2022•0 citations

Laser-cooled polyatomic molecules for improved electron electric dipole moment searches

Benjamin L. Augenbraun, Zack Lasner, Alexander Frenett +4 more

Abstract Doppler and Sisyphus cooling of 174YbOH are achieved and studied. This polyatomic molecule has high sensitivity to physics beyond the Standard Model and represents a new class of species for future high-precision probes of new T-violating physics. The transverse temperature of the YbOH beam is reduced by nearly two orders of magnitude to < 600 μK and the phase-space density is increased by a factor of > 6 via Sisyphus cooling. We develop a full numerical model of the laser cooling of YbOH and find excellent agreement with the data. We project that laser cooling and magneto-optical trapping of long-lived samples of YbOH molecules are within reach and these will allow a high sensitivity probe of the electric dipole moment of the electron. The approach demonstrated here is easily generalized to other isotopologues of YbOH that have enhanced sensitivity to other symmetry-violating electromagnetic moments.

arXiv:1910.11318•New Journal of Physics•Jan 7, 2020•163 citations
Ultracold polyatomic molecules containing heavy nuclei, such as SrOH and YbOH, are sensitive to T- symmetry violating and P-symmetry violating physics beyond the Standard Model through the electron’s electric dipole moment. Furthermore, SrOH is sensitive to ultralight Dark Matter through measuring time variations of fundamental constants. However, in order to make full use of these molecules, they need to be cooled to ultracold temperatures and held in optical traps. We have realized a magneto-optical trap (MOT) of SrOH and used this as the essential element to achieve optical trap- ping in the microKelvin temperature regime. We observed MOT lifetimes approaching 200 ms with temperatures ∼ 1 mK and observed damped oscillations in the MOT. We further cooled the SrOH molecules to ∼ 40 μ K using Λ-enhanced gray molasses, and compressed the cloud to about 100 μm size using the conveyor belt MOT technique. Using this ultracold dense cloud of SrOH, we loaded an optical dipole trap (ODT), with a molecular lifetime of 1.2(1) seconds. In separate experiments with YbOH, which is heavier than SrOH, we demonstrated a novel deceleration method (Zeeman- Sisyphus deceleration) that can slow YbOH to under 20 m/s with only a few photons scattered utilizing high magnetic fields up to 2.5 T. By driving spin-flip transitions at the maxima and minima of the magnetic fields, slowing was achieved, which is a critical first step toward loading of a MOT for this species. We addressed the challenges associated with driving spin-flip transitions in molecules that have molecular perturbations among the electronic excited states and developed an understanding of the physics of such systems that is applicable to a wide range of molecules.
Polyatomic molecules are promising platforms for conducting precision measurements to probe the Standard Model, owing to their unique degrees of freedom including vibrations and rotations. In particular, ultracold SrOH has sensitivity to the variation of the proton to electron mass ratio μ\muμ and subsequently to scalar ultralight dark matter (UDM) fields. We discuss the laser slowing, sub-Doppler cooling, and trapping of SrOH and present an order of magnitude improved trap number through the use of transverse cooling of the molecular beam resulting in ∼\sim∼10410^4104 optically trapped molecules. This would allow for a two order of magnitude improvement on the current best sensitivities to UDM over four decades of mass. Probing μ\muμ-variation is not only important for UDM studies, but has more general implications for a variety of fundamental physics searches. Additionally, this increase in trapped molecule number makes SrOH a viable candidate in the search for the electron's electric dipole moment (eeeEDM) for fundamental symmetry violations. These techniques are broadly applicable, and make cooling and trapping heavier and more complex molecules with greater sensitivity to fundamental physics more viable.
We report a magneto-optical trap of strontium monohydroxide (SrOH) containing 2000(600) molecules at a temperature of 1.2(3) mK. The lifetime is 91(9) ms, which is limited by decay to optically unaddressed vibrational states. This provides the foundation for future sub-Doppler cooling and optical trapping of SrOH, a polyatomic molecule suited for precision searches for physics beyond the standard model including new CP violating particles and ultralight dark matter. We also identify important features in this system that guide cooling and trapping of complex and heavy polyatomic molecules into the ultracold regime.
Extending AMO techniques of motional control to heavy polyatomic molecules opens new possibilities for precision measurements of fundamental physics. Though various laser-cooling and deceleration techniques have been applied to diatomic molecules throughout the last decade, their application to more complex molecules has heretofore been focused on light species, leaving generalizability to heavy species an open question. To investigate the high-mass frontier, we here study how to extend motional control to heavy-atom-containing polyatomic molecules. First, we discuss Zeeman-Sisyphus deceleration of YbOH, which can be used to decelerate species capable of scattering only ~10s of photons. Then, we discuss radiative slowing and magneto-optical trapping of SrOH, techniques only extendable to species capable of scattering ∼104\sim10^4∼104 photons. The last work focuses on spectroscopy of nonlinear molecules to assess the viability of extending techniques of motional control to more complex species. We find a dependence of both rotational and vibrational control on symmetry group, and identify a next-generation candidate for laser cooling. We end with a overview tying these projects together, and assessing the future of motional control along mass and complexity axes, including brief suggestions of how complementary methods to those studied here can further expand into the frontiers of molecular control.
We demonstrate a two-dimensional Sisyphus laser cooling method that increases the number of strontium monohydroxide (SrOH) molecules loaded into a magneto-optical trap by a factor of 12. Subsequent loading into an optical dipole trap (ODT) achieves 2.2(3)×1042.2 (3)\times10^42.2(3)×104 ultracold SrOH molecules with a peak density of ∼2(1)×1010 cm−3\sim2(1)\times10^{10}~\mathrm{cm^{-3}}∼2(1)×1010 cm−3. The lifetime of molecules in the ODT is limited by two-body collisions characterized by a measured collision rate constant β∼4×10−10 cm3/sβ\sim 4\times10^{-10}~\mathrm{cm^3/s}β∼4×10−10 cm3/s. The cooling method developed here is generally applicable to all known cases of direct molecular laser cooling, including symmetric and asymmetric top molecules. Increases in trapped molecule number will directly improve the search for ultralight dark matter, position polyatomic molecules as a platform for probing CP-violating new particles with masses $\gg$10 TeV, and facilitate a broad range of further research in quantum science.
Molecules controlled at the single-quantum-state level offer wide-ranging applications spanning many of the frontiers of modern physics. Within the past decade, simple diatomic molecules have been brought under full quantum control both via assembly from pre-cooled atoms and by direct laser cooling. Polyatomic molecules\footnote{Molecules that contain three or more atoms.} have attracted focus as novel quantum resources providing distinct advantages (and challenges) compared to both atoms and diatomic molecules. For example, nearly all polyatomic molecules have long-lived states that can be fully polarized at low applied electric fields. These and other features generic to polyatomic molecules can be applied to quantum simulation, quantum chemistry, and tests of fundamental physics beyond the Standard Model. While these structural features of polyatomic molecules are highly promising for applications, they complicate the process of bringing molecules under full quantum control. In this thesis, we describe a series of experimental and theoretical advances toward the production of ultracold complex polyatomic molecules. We demonstrate the first laser cooling of the polyatomic radical ytterbium monohydroxide (YbOH), a promising candidate to search for particles and interactions beyond the Standard Model of particle physics. We develop a novel deceleration technique (``Zeeman-Sisyphus deceleration") capable of slowing molecular beams to trappable velocities while scattering fewer than 10 optical photons. This deceleration method is demonstrated using CaOH molecules, a lighter analog of YbOH. In order to determine a viable pathway to full three-dimensional cooling and trapping of YbOH, we develop a spectroscopic technique to measure vibrational branching ratios with relative intensity sensitivity around 1 part in 10510^5105, approximately two orders of magnitude beyond the previous state of the art. We also perform the first spectroscopic observations and characterizations of the related molecule ytterbium monomethoxide, YbOCH3_33​, a promising species to probe beyond-the-Standard-Model physics. In addition, we show theoretically that an entire class of asymmetric top molecules can be laser cooled using essentially the same techniques used for much simpler species. Measurements of the vibrational branching ratios for a few prototypical asymmetric to molecules (CaSH and CaNH2_22​) are presented to confirm these predictions.
Abstract Doppler and Sisyphus cooling of 174YbOH are achieved and studied. This polyatomic molecule has high sensitivity to physics beyond the Standard Model and represents a new class of species for future high-precision probes of new T-violating physics. The transverse temperature of the YbOH beam is reduced by nearly two orders of magnitude to < 600 μK and the phase-space density is increased by a factor of > 6 via Sisyphus cooling. We develop a full numerical model of the laser cooling of YbOH and find excellent agreement with the data. We project that laser cooling and magneto-optical trapping of long-lived samples of YbOH molecules are within reach and these will allow a high sensitivity probe of the electric dipole moment of the electron. The approach demonstrated here is easily generalized to other isotopologues of YbOH that have enhanced sensitivity to other symmetry-violating electromagnetic moments.