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:2205.06165 · Physical Review A

Vibrational ladder-descending photostabilization of a weakly bound molecule: Quantum optimal control with a genetic algorithm

Mateo Londoño, J. C. Arce

Published Jul 5, 2023• 3 citations
arXivHTMLPDF

Abstract

We propose an optical control scheme for driving a polar diatomic molecule from a high-lying vibrational level to a target low-lying one, within the same electronic state. The scheme utilizes an infrared chirped laser pulse with an analytical shape, whose parameters are optimized by means of a heuristic formulation of quantum optimal control based on a genetic algorithm. We illustrate this methodology computationally for a KRb Feshbach molecule in the lowest triplet electronic state.

DOI
10.1103/physreva.108.013301

Related papers

Rovibrational wave-packet manipulation using shaped midinfrared femtosecond pulses toward quantum computation: Optimization of pulse shape by a genetic algorithm

Masaaki Tsubouchi, Takamasa Momose

We have numerically examined optimization of the experimentally achievable shapes of mid-infrared femtosecond laser pulses to construct elementary quantum gates using molecular rovibrational states of a single molecule. Instead of optimizing the electric field by optimal control theory, the method generally used in theoretical studies of coherent control, the transmittance and the phase shift of conventional pulse shapers were optimized in the frequency domain by a genetic algorithm. The target molecular system we examined was the rotation-vibration states of CO in the $X({^{1}\ensuremath{\Sigma}}^{+})$ ground electronic state. Although the existence of the rotational degrees of freedom makes the quantum gate operation complicated, high fidelity of over 0.95 was achieved for one-rovibrational-qubit systems, which indicates that a molecular quantum computer may be feasible for at least one-qubit calculations on a diatomic molecule. On the other hand, two-qubit calculations are more difficult to achieve in a single CO molecule using rotational and vibrational degrees of freedom as different qubits. The importance of the control of the rotational in addition to the vibrational wave packet in order to realize a molecular quantum computer is discussed.

Physical Review A•May 20, 2008•57 citations

Photostabilization of ultracold Rb2 molecules by optimal control

Boris Schäfer-Bung, Roland Mitrić, Vlasta Bonačić‐Koutecký

We present a theoretical study of the photostabilization of the ultracold Rb2 molecule by tailored laser fields. The simulations involve the ground and two excited electronic states, taking into account spin–orbit coupling, and are based on the full quantum mechanical optimal control theory. We demonstrate starting from a highly excited bound vibrational state that almost 100% population of the ground state v = 0 vibrational level can be achieved. The obtained optimal pulse has a long temporal and very broad spectral range. Our results reveal the mechanism of the photostabilization process and allow the proposal of new strategies for the formation of ultracold molecules taking into account the necessary constraints for possible experimental realization.

•Sep 25, 2006•0 citations

Vibrational stabilization of ultracold KRb molecules: A comparative study

Mamadou Ndong, Christiane P. Koch

The transfer of weakly bound KRb molecules from levels just below the dissociation threshold into the vibrational ground state with shaped laser pulses is studied. Optimal control theory is employed to calculate the pulses. The complexity of modeling the molecular structure is successively increased in order to study the effects of the long-range behavior of the excited-state potential, resonant spin-orbit coupling, and singlet-triplet mixing.

arXiv:1007.1898•Physical Review A•Oct 29, 2010•28 citations

Photostabilization of the ultracold Rb2molecule by optimal control

Boris Schäfer-Bung, Roland Mitrić, Vlasta Bonačić‐Koutecký

We present a theoretical study of the photostabilization of the ultracold Rb 2 molecule by tailored laser fields. The simulations involve the ground and two excited electronic states, taking into account spin–orbit coupling, and are based on the full quantum mechanical optimal control theory. We demonstrate starting from a highly excited bound vibrational state that almost 100% population of the ground state v = 0 vibrational level can be achieved. The obtained optimal pulse has a long temporal and very broad spectral range. Our results reveal the mechanism of the photostabilization process and allow the proposal of new strategies for the formation of ultracold molecules taking into account the necessary constraints for possible experimental realization.

Journal of Physics B Atomic Molecular and Optical Physics•Sep 25, 2006•6 citations

Formation of deeply bound polar molecules combining pump-dump pulses with infrared radiation

Emanuel F. de Lima

We consider the formation of cold ground-state polar molecules in a low vibrational level by laser fields. Starting from a pair of cold colliding atoms of dissimilar species, we propose a strategy consisting of three steps. In the first step, a pump pulse induces the molecule formation by photoassociating the atomic pair in a high or intermediate vibrational level of an excited electronic molecular state. This step is followed by a dump pulse in an intermediate vibrational level of the ground state. The last step corresponds to the vibrational cooling or vibrational stabilization process. Taking advantage of the permanent dipole moment, an infrared chirped pulse induces downward transitions among the vibrational levels of the ground electronic state, reaching the ground vibrational level. We perform the strategy with with fixed-shaped pulses and also with an optimized chirped pulse for the stabilization step. To perform the optimization, we introduce an optimal control technique in which the optimization of the chirping is carried out in the time domain. This methodology has the benefit of limiting the pulse amplitude while focusing only on the frequency of the field. The proposed scheme is an alternative to the use of two pairs of pump-dump pulses or to the direct photoassociation and vibrational stabilization in the ground state.

arXiv:2308.11085•Physical Review A•Jan 18, 2024•2 citations

Quantum computation with vibrationally excited polyatomic molecules: effects of rotation, level structure, and field gradients

Daniel Weidinger, Martin Gruebele

Accurate rotation–vibration energy levels and transition dipoles of the molecule thiophosgene are used to model the execution of quantum gates with shaped laser pulses. Qubits are encoded in 2 n vibrational computing states on the ground electronic surface of the molecule. Computations are carried out by cycling amplitude between these computing states and a gateway state with a shaped laser pulse. The shaped pulse that performs the computation is represented by a physical model of a 128–1024 channel pulse shaper. Pulse shapes are optimized with a standard genetic algorithm, yielding experimentally realizable computing pulses. The robustness of optimization is studied as a function of the vibrational states selected, rotational level structure, additional vibrational levels not assigned to the computation, and compensation for laser power variation across a molecular ensemble.

Molecular Physics•Jul 10, 2007•38 citations
We propose an optical control scheme for driving a polar diatomic molecule from a high-lying vibrational level to a target low-lying one, within the same electronic state. The scheme utilizes an infrared chirped laser pulse with an analytical shape, whose parameters are optimized by means of a heuristic formulation of quantum optimal control based on a genetic algorithm. We illustrate this methodology computationally for a KRb Feshbach molecule in the lowest triplet electronic state.
We have numerically examined optimization of the experimentally achievable shapes of mid-infrared femtosecond laser pulses to construct elementary quantum gates using molecular rovibrational states of a single molecule. Instead of optimizing the electric field by optimal control theory, the method generally used in theoretical studies of coherent control, the transmittance and the phase shift of conventional pulse shapers were optimized in the frequency domain by a genetic algorithm. The target molecular system we examined was the rotation-vibration states of CO in the $X({^{1}\ensuremath{\Sigma}}^{+})$ ground electronic state. Although the existence of the rotational degrees of freedom makes the quantum gate operation complicated, high fidelity of over 0.95 was achieved for one-rovibrational-qubit systems, which indicates that a molecular quantum computer may be feasible for at least one-qubit calculations on a diatomic molecule. On the other hand, two-qubit calculations are more difficult to achieve in a single CO molecule using rotational and vibrational degrees of freedom as different qubits. The importance of the control of the rotational in addition to the vibrational wave packet in order to realize a molecular quantum computer is discussed.
We present a theoretical study of the photostabilization of the ultracold Rb2 molecule by tailored laser fields. The simulations involve the ground and two excited electronic states, taking into account spin–orbit coupling, and are based on the full quantum mechanical optimal control theory. We demonstrate starting from a highly excited bound vibrational state that almost 100% population of the ground state v = 0 vibrational level can be achieved. The obtained optimal pulse has a long temporal and very broad spectral range. Our results reveal the mechanism of the photostabilization process and allow the proposal of new strategies for the formation of ultracold molecules taking into account the necessary constraints for possible experimental realization.
We present a theoretical study of the photostabilization of the ultracold Rb 2 molecule by tailored laser fields. The simulations involve the ground and two excited electronic states, taking into account spin–orbit coupling, and are based on the full quantum mechanical optimal control theory. We demonstrate starting from a highly excited bound vibrational state that almost 100% population of the ground state v = 0 vibrational level can be achieved. The obtained optimal pulse has a long temporal and very broad spectral range. Our results reveal the mechanism of the photostabilization process and allow the proposal of new strategies for the formation of ultracold molecules taking into account the necessary constraints for possible experimental realization.
We consider the formation of cold ground-state polar molecules in a low vibrational level by laser fields. Starting from a pair of cold colliding atoms of dissimilar species, we propose a strategy consisting of three steps. In the first step, a pump pulse induces the molecule formation by photoassociating the atomic pair in a high or intermediate vibrational level of an excited electronic molecular state. This step is followed by a dump pulse in an intermediate vibrational level of the ground state. The last step corresponds to the vibrational cooling or vibrational stabilization process. Taking advantage of the permanent dipole moment, an infrared chirped pulse induces downward transitions among the vibrational levels of the ground electronic state, reaching the ground vibrational level. We perform the strategy with with fixed-shaped pulses and also with an optimized chirped pulse for the stabilization step. To perform the optimization, we introduce an optimal control technique in which the optimization of the chirping is carried out in the time domain. This methodology has the benefit of limiting the pulse amplitude while focusing only on the frequency of the field. The proposed scheme is an alternative to the use of two pairs of pump-dump pulses or to the direct photoassociation and vibrational stabilization in the ground state.
Accurate rotation–vibration energy levels and transition dipoles of the molecule thiophosgene are used to model the execution of quantum gates with shaped laser pulses. Qubits are encoded in 2 n vibrational computing states on the ground electronic surface of the molecule. Computations are carried out by cycling amplitude between these computing states and a gateway state with a shaped laser pulse. The shaped pulse that performs the computation is represented by a physical model of a 128–1024 channel pulse shaper. Pulse shapes are optimized with a standard genetic algorithm, yielding experimentally realizable computing pulses. The robustness of optimization is studied as a function of the vibrational states selected, rotational level structure, additional vibrational levels not assigned to the computation, and compensation for laser power variation across a molecular ensemble.