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

Journal of Physics B Atomic Molecular and Optical Physics

Selective control of molecular rotation

Sharly Fleischer, Ilya Sh. Averbukh, Yehiam Prior

Published Mar 26, 2008• 28 citations
Publisher

Abstract

We demonstrate selective control over rotational motion of small, linear molecules. By means of sequential excitation of the rotational motion by ultrashort pulses, we first prepare transiently aligned molecules with periodically revived angular distribution. Upon further, properly timed excitation, the rotational energy can be increased or decreased, depending on the exact timing of the second pulse. We show how this approach can be applied for selective rotational control of a single component in a molecular mixture. We discuss this selectivity in the context of molecular isotopes ( 14 N 2 , 15 N 2 ), where the difference in isotopic mass gives rise to different rotational revival times. We further apply the method to the selective addressing of molecular spin isomers (para, ortho 15 N 2 ) in a mixture, where wavefunction symmetry differences replace the mass differences as the origin of the selectivity. In both cases the method is demonstrated experimentally and the results are analysed theoretically.

DOI
10.1088/0953-4075/41/7/074018

Related papers

Directional spinning of molecules with sequences of femtosecond pulses

Casey Kyle Bloomquist, Sergey Zhdanovich, A. Milner +1 more

We present an analysis of two experimental approaches to controlling the directionality of molecular rotation with ultrashort laser pulses. The two methods are based on the molecular interaction with either a pair of pulses (a ``double-kick'' scheme) or a longer pulse sequence (a ``chiral-pulse-train'' scheme). In both cases, rotational control is achieved by varying the polarization of and the time delay between the consecutive laser pulses. Using the technique of polarization-sensitive resonance-enhanced multiphoton ionization, we show that both methods produce significant rotational directionality. We demonstrate that increasing the number of excitation pulses supplements the ability to control the sense of molecular rotation with quantum-state selectivity, i.e., predominant excitation of a single rotational state. We also demonstrate the ability of both techniques to generate counterrotation of molecular nuclear-spin isomers (here, ortho- and para-nitrogen) and molecular isotopologs (here, ${}^{14}$N${}_{2}$ and ${}^{15}$N${}_{2}$).

arXiv:1208.4345•Physical Review A•Dec 19, 2012•27 citations

Controlling the sense of molecular rotation

Sharly Fleischer, Yuri Khodorkovsky, Yehiam Prior +1 more

We introduce a new scheme for controlling the sense of molecular rotation. By varying the polarization and the delay between two ultrashort laser pulses, we induce unidirectional molecular rotation, thereby forcing the molecules to rotate clockwise/counterclockwise under field-free conditions. We show that unidirectionally rotating molecules are confined to the plane defined by the two polarization vectors of the pulses, which leads to a permanent anisotropy in the molecular angular distribution. The latter may be useful for controlling collisional cross-sections and optical and kinetic processes in molecular gases. We discuss the application of this control scheme to individual components within a molecular mixture in a selective manner.

arXiv:0907.5300•New Journal of Physics•Oct 30, 2009•117 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

Optical Control of the Rotational Angular Momentum of a Molecular Rydberg Wave Packet

Russell S. Minns, R. Patel, Jan R. R. Verlet +1 more

An intuitive scheme for controlling the rotational quantum state of a Rydberg molecule is demonstrated experimentally. We determine the accumulated phase difference between the various components of a molecular electron wave packet, and then employ a sequence of phase-locked optical pulses to selectively enhance or depopulate specific rotational states. The angular momentum composition of the resulting wave packet, and the efficiency of the control scheme, is determined by calculating the multipulse response of the time-dependent Rydberg populations.

Physical Review Letters•Dec 10, 2003•30 citations

Quantum control of isotope-selective molecular orientation

Yuzuru Kurosaki, Keiichi Yokoyama, Yukiyoshi Ohtsuki

We investigate quantum control of isotope-selective molecular orientation using optimal control theory. The target in this study is to inversely orient two isotopologues, 7Li37Cl and 7Li35Cl, along the field polarization vector. The Hamiltonian includes dipole and polarization interactions and we prepare two laser sources, one of which is responsible for resonant transitions through the dipole interaction and the other is stronger and responsible for nonresonant transitions through the polarization interaction. Total time of the control pulse is set to twice the rotational period that is defined as the inverse of the J = 1 ← 0 transition frequency (J: the rotational quantum number). As a result of the calculation at 0 K, an optimal field leads to the expectation values of cosθ (θ: the angle between the field polarization vector and the molecular axis) for the two isotopologues, 0.76 and -0.78, indicating that the control is successful. It is found that in the optimal field the resonant and nonresonant pulses cooperatively interact with the molecules to enhance the control efficiency.

AIP conference proceedings•Jan 1, 2022•1 citation

Selective excitation of atoms and molecules by ultrashort laser pulses

Anahit L. Gogyan, Yuri P. Malakyan

Efficient excitation of an ensemble of atoms and molecules to a desired state is of fundamental importance not only for spectroscopy but also for quantum control of molecular dynamics in chemical and biological processes. The latter usually occurs on a much shorter time scale (in the femtosecond range) giving rise to steadily advanced problem how to excite one of the nearby levels, even when they are well within the broad fs pulse spectrum. We propose a new effective method for selective excitation of atoms based on the atomic coherence and discuss a sensitive method to verify experimentally the proposed mechanism using the technique of quantum beating in pump-probe experiments.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Dec 22, 2008•1 citation
We demonstrate selective control over rotational motion of small, linear molecules. By means of sequential excitation of the rotational motion by ultrashort pulses, we first prepare transiently aligned molecules with periodically revived angular distribution. Upon further, properly timed excitation, the rotational energy can be increased or decreased, depending on the exact timing of the second pulse. We show how this approach can be applied for selective rotational control of a single component in a molecular mixture. We discuss this selectivity in the context of molecular isotopes ( 14 N 2 , 15 N 2 ), where the difference in isotopic mass gives rise to different rotational revival times. We further apply the method to the selective addressing of molecular spin isomers (para, ortho 15 N 2 ) in a mixture, where wavefunction symmetry differences replace the mass differences as the origin of the selectivity. In both cases the method is demonstrated experimentally and the results are analysed theoretically.
We present an analysis of two experimental approaches to controlling the directionality of molecular rotation with ultrashort laser pulses. The two methods are based on the molecular interaction with either a pair of pulses (a ``double-kick'' scheme) or a longer pulse sequence (a ``chiral-pulse-train'' scheme). In both cases, rotational control is achieved by varying the polarization of and the time delay between the consecutive laser pulses. Using the technique of polarization-sensitive resonance-enhanced multiphoton ionization, we show that both methods produce significant rotational directionality. We demonstrate that increasing the number of excitation pulses supplements the ability to control the sense of molecular rotation with quantum-state selectivity, i.e., predominant excitation of a single rotational state. We also demonstrate the ability of both techniques to generate counterrotation of molecular nuclear-spin isomers (here, ortho- and para-nitrogen) and molecular isotopologs (here, 14{}^{14}14N2{}_{2}2​ and 15{}^{15}15N2{}_{2}2​).
We introduce a new scheme for controlling the sense of molecular rotation. By varying the polarization and the delay between two ultrashort laser pulses, we induce unidirectional molecular rotation, thereby forcing the molecules to rotate clockwise/counterclockwise under field-free conditions. We show that unidirectionally rotating molecules are confined to the plane defined by the two polarization vectors of the pulses, which leads to a permanent anisotropy in the molecular angular distribution. The latter may be useful for controlling collisional cross-sections and optical and kinetic processes in molecular gases. We discuss the application of this control scheme to individual components within a molecular mixture in a selective manner.
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.
An intuitive scheme for controlling the rotational quantum state of a Rydberg molecule is demonstrated experimentally. We determine the accumulated phase difference between the various components of a molecular electron wave packet, and then employ a sequence of phase-locked optical pulses to selectively enhance or depopulate specific rotational states. The angular momentum composition of the resulting wave packet, and the efficiency of the control scheme, is determined by calculating the multipulse response of the time-dependent Rydberg populations.
We investigate quantum control of isotope-selective molecular orientation using optimal control theory. The target in this study is to inversely orient two isotopologues, 7Li37Cl and 7Li35Cl, along the field polarization vector. The Hamiltonian includes dipole and polarization interactions and we prepare two laser sources, one of which is responsible for resonant transitions through the dipole interaction and the other is stronger and responsible for nonresonant transitions through the polarization interaction. Total time of the control pulse is set to twice the rotational period that is defined as the inverse of the J = 1 ← 0 transition frequency (J: the rotational quantum number). As a result of the calculation at 0 K, an optimal field leads to the expectation values of cosθ (θ: the angle between the field polarization vector and the molecular axis) for the two isotopologues, 0.76 and -0.78, indicating that the control is successful. It is found that in the optimal field the resonant and nonresonant pulses cooperatively interact with the molecules to enhance the control efficiency.
Efficient excitation of an ensemble of atoms and molecules to a desired state is of fundamental importance not only for spectroscopy but also for quantum control of molecular dynamics in chemical and biological processes. The latter usually occurs on a much shorter time scale (in the femtosecond range) giving rise to steadily advanced problem how to excite one of the nearby levels, even when they are well within the broad fs pulse spectrum. We propose a new effective method for selective excitation of atoms based on the atomic coherence and discuss a sensitive method to verify experimentally the proposed mechanism using the technique of quantum beating in pump-probe experiments.