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

arXiv:1504.01432 · Journal of Physics B Atomic Molecular and Optical Physics

Dynamics of molecular superrotors in an external magnetic field

Aleksey Korobenko, Valery Milner

Published Jul 15, 2015• 16 citations
arXivHTMLPDF

Abstract

Abstract We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin–rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation.

DOI
10.1088/0953-4075/48/16/164004

Related papers

Magneto-Optical Properties of Paramagnetic Superrotors

A. Milner, Aleksey Korobenko, Johannes Floß +2 more

We study the dynamics of paramagnetic molecular superrotors in an external magnetic field. An optical centrifuge is used to create dense ensembles of oxygen molecules in ultrahigh rotational states. In is shown, for the first time, that the gas of rotating molecules becomes optically birefringent in the presence of a magnetic field. The discovered effect of "magneto-rotational birefringence" indicates the preferential alignment of molecular axes along the field direction. We provide an intuitive qualitative model, in which the influence of the applied magnetic field on the molecular orientation is mediated by the spin-rotation coupling. This model is supported by the direct imaging of the distribution of molecular axes, the demonstration of the magnetic reversal of the rotational Raman signal, and by numerical calculations.

arXiv:1410.4257•Physical Review Letters•Jul 14, 2015•21 citations

Nonlinear dynamics of molecular superrotors

C. Chandré, J. Pablo Salas

We consider a diatomic molecule driven by a linearly polarized laser pulse with a polarization axis rotating with a constant acceleration. This setup is referred to as optical centrifuge, and it is known to lead to high-angular momenta for the molecule (superrotor states) and, possibly, to dissociation. Here we elucidate the dynamical mechanisms behind the creation of superrotor states and their dissociation. We unravel the role of the various parameters of the laser field in these processes by considering reduced Hamiltonian models encapsulating the different phases in the creation of superrotor states, possibly leading to dissociation.

arXiv:2303.05090•Physical Review A•Jun 8, 2023•2 citations

Coherent Control of the Rotation Axis of Molecular Superrotors

Alec Owens, Andrey Yachmenev, Jochen Küpper

The control of ultrafast molecular rotational motion has benefited from the development of innovative techniques in strong-field laser physics. Here, we theoretically demonstrate a novel type of coherent control by inducing rotation of an asymmetric-top molecule about two different molecular axes. An optical centrifuge is applied to the hydrogen sulfide (H 2 S) molecule to create a molecular superrotor, an object performing ultrafast rotation about a well-defined axis. Using two distinct pulse envelopes for the optical centrifuge, we show that H 2 S can be excited along separate pathways of rotational states. This leads to stable rotation about two entirely different molecular axes while ensuring rotation is about the propagation direction of the centrifuge, i.e., the laboratory-fixed Z -axis. The presented scheme to control the angular momentum alignment of a molecule will, for instance, be useful in studies of molecule–molecule or molecule–surface scattering, especially due to the large amounts of energy associated with superrotors, which can even be controlled by changing the duration of the optical centrifuge pulse.

arXiv:1807.04016•The Journal of Physical Chemistry Letters•Jul 11, 2018•12 citations

Control of molecular rotation in the limit of extreme rotational excitation

Valery Milner, J. W. Hepburn

Laser control of molecular rotation is an area of active research. A number of recent studies has aimed at expanding the reach of rotational control to extreme, previously inaccessible rotational states, as well as controlling the directionality of molecular rotation. Dense ensembles of molecules undergoing ultrafast uni-directional rotation, known as molecular superrotors, are anticipated to exhibit unique properties, from spatially anisotropic diffusion and vortex formation to the creation of powerful acoustic waves and tuneable THz radiation. Here we describe our recent progress in controlling molecular rotation in the regime of high rotational excitation. We review two experimental techniques of producing uni-directional rotational wave packets with a "chiral train" of femtosecond pulses and an "optical centrifuge". Three complementary detection methods, enabling the direct observation, characterization and control of the superrotor states, are outlined: the one based on coherent Raman scattering, and two other methods employing both resonant and non-resonant multi-photon ionization. The capabilities of the described excitation and detection techniques are demonstrated with a few examples. The paper is concluded with an outlook for future developments.

arXiv:1501.02739•Jan 12, 2015•1 citation

Ultrafast Magnetization of a Dense Molecular Gas with an Optical Centrifuge

A. Milner, Aleksey Korobenko, Valery Milner

Strong laser-induced magnetization of oxygen gas at room temperature and atmospheric pressure is achieved experimentally on the subnanosecond time scale. The method is based on controlling the electronic spin of paramagnetic molecules by means of manipulating their rotation with an optical centrifuge. Spin-rotational coupling results in a high degree of spin polarization on the order of one Bohr magneton per centrifuged molecule. Owing to the nonresonant interaction with the laser pulses, the demonstrated technique is applicable to a broad class of paramagnetic rotors. Executed in a high-density gas, it may offer an efficient way of generating macroscopic magnetic fields remotely (as shown in this work) and producing a large amount of spin-polarized electrons.

arXiv:1612.05328•Physical Review Letters•Jun 16, 2017•22 citations

Zero field splittings in paramagnetic dysprosium dimers

Hui Li, Eite Tiesinga, Ming Li +2 more

Zero field splittings in molecules originate from the intrinsic spin and orbital angular momentum of unpaired electrons. Here, we close a knowledge gap on a diatomic molecule built from spin-8 ground-state dysprosium atoms, where zero-field splittings correspond to the energies of states with different alignments of the two spins. We predict a paramagnetic molecular ground state with parallel Dy spins aligned along the internuclear axis. A diamagnetic state with anti-parallel spins is the first excited state with a small energy cost of hc × 2 cm−1 predominantly due to the magnetic dipole-dipole interaction. We also determine the rotations and vibrations of the diatom and show that centrifugal forces double the splittings between these para- and dia-magnetic states. The vibrational spacings and zero-field splittings have similar magnitude. Finally, the Dy2 ground state has a magnetic moment that is twice that of the atom and, thus, arrays of ultracold Dy2 can be used to simulate strongly interacting magnets. Zero-field splittings in molecules arise from the spin and orbital angular momentum of unpaired electrons, yet their behaviour in diatomic molecules with spin-8 dysprosium atoms remains underexplored. Here, the authors predict a paramagnetic ground state with parallel Dy spins and reveal implications for simulating strongly interacting magnets using ultracold Dy2 arrays.

Communications Physics•May 28, 2026•1 citation
Abstract We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin–rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation.
We study the dynamics of paramagnetic molecular superrotors in an external magnetic field. An optical centrifuge is used to create dense ensembles of oxygen molecules in ultrahigh rotational states. In is shown, for the first time, that the gas of rotating molecules becomes optically birefringent in the presence of a magnetic field. The discovered effect of "magneto-rotational birefringence" indicates the preferential alignment of molecular axes along the field direction. We provide an intuitive qualitative model, in which the influence of the applied magnetic field on the molecular orientation is mediated by the spin-rotation coupling. This model is supported by the direct imaging of the distribution of molecular axes, the demonstration of the magnetic reversal of the rotational Raman signal, and by numerical calculations.
We consider a diatomic molecule driven by a linearly polarized laser pulse with a polarization axis rotating with a constant acceleration. This setup is referred to as optical centrifuge, and it is known to lead to high-angular momenta for the molecule (superrotor states) and, possibly, to dissociation. Here we elucidate the dynamical mechanisms behind the creation of superrotor states and their dissociation. We unravel the role of the various parameters of the laser field in these processes by considering reduced Hamiltonian models encapsulating the different phases in the creation of superrotor states, possibly leading to dissociation.
The control of ultrafast molecular rotational motion has benefited from the development of innovative techniques in strong-field laser physics. Here, we theoretically demonstrate a novel type of coherent control by inducing rotation of an asymmetric-top molecule about two different molecular axes. An optical centrifuge is applied to the hydrogen sulfide (H 2 S) molecule to create a molecular superrotor, an object performing ultrafast rotation about a well-defined axis. Using two distinct pulse envelopes for the optical centrifuge, we show that H 2 S can be excited along separate pathways of rotational states. This leads to stable rotation about two entirely different molecular axes while ensuring rotation is about the propagation direction of the centrifuge, i.e., the laboratory-fixed Z -axis. The presented scheme to control the angular momentum alignment of a molecule will, for instance, be useful in studies of molecule–molecule or molecule–surface scattering, especially due to the large amounts of energy associated with superrotors, which can even be controlled by changing the duration of the optical centrifuge pulse.
Laser control of molecular rotation is an area of active research. A number of recent studies has aimed at expanding the reach of rotational control to extreme, previously inaccessible rotational states, as well as controlling the directionality of molecular rotation. Dense ensembles of molecules undergoing ultrafast uni-directional rotation, known as molecular superrotors, are anticipated to exhibit unique properties, from spatially anisotropic diffusion and vortex formation to the creation of powerful acoustic waves and tuneable THz radiation. Here we describe our recent progress in controlling molecular rotation in the regime of high rotational excitation. We review two experimental techniques of producing uni-directional rotational wave packets with a "chiral train" of femtosecond pulses and an "optical centrifuge". Three complementary detection methods, enabling the direct observation, characterization and control of the superrotor states, are outlined: the one based on coherent Raman scattering, and two other methods employing both resonant and non-resonant multi-photon ionization. The capabilities of the described excitation and detection techniques are demonstrated with a few examples. The paper is concluded with an outlook for future developments.
Strong laser-induced magnetization of oxygen gas at room temperature and atmospheric pressure is achieved experimentally on the subnanosecond time scale. The method is based on controlling the electronic spin of paramagnetic molecules by means of manipulating their rotation with an optical centrifuge. Spin-rotational coupling results in a high degree of spin polarization on the order of one Bohr magneton per centrifuged molecule. Owing to the nonresonant interaction with the laser pulses, the demonstrated technique is applicable to a broad class of paramagnetic rotors. Executed in a high-density gas, it may offer an efficient way of generating macroscopic magnetic fields remotely (as shown in this work) and producing a large amount of spin-polarized electrons.
Zero field splittings in molecules originate from the intrinsic spin and orbital angular momentum of unpaired electrons. Here, we close a knowledge gap on a diatomic molecule built from spin-8 ground-state dysprosium atoms, where zero-field splittings correspond to the energies of states with different alignments of the two spins. We predict a paramagnetic molecular ground state with parallel Dy spins aligned along the internuclear axis. A diamagnetic state with anti-parallel spins is the first excited state with a small energy cost of hc × 2 cm−1 predominantly due to the magnetic dipole-dipole interaction. We also determine the rotations and vibrations of the diatom and show that centrifugal forces double the splittings between these para- and dia-magnetic states. The vibrational spacings and zero-field splittings have similar magnitude. Finally, the Dy2 ground state has a magnetic moment that is twice that of the atom and, thus, arrays of ultracold Dy2 can be used to simulate strongly interacting magnets. Zero-field splittings in molecules arise from the spin and orbital angular momentum of unpaired electrons, yet their behaviour in diatomic molecules with spin-8 dysprosium atoms remains underexplored. Here, the authors predict a paramagnetic ground state with parallel Dy spins and reveal implications for simulating strongly interacting magnets using ultracold Dy2 arrays.