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

BENTHAM SCIENCE PUBLISHERS eBooks

Cold Molecules, Photoassociation, Optical Pumping and Laser Cooling: The Cesium Case

Bentham Science Publisher Bentham Science Publisher

Published Mar 13, 2012• 0 citations
Publisher

Abstract

The cold-molecule field concerns the physics and the applications of molecular systems with translational temperature well below the 1 К range. The possibility of controlling all the motion as well as the internal quantum state of a sample of molecules is a long-term goal that opens the possibility for many new experiments and measurements ranging from fundamental constants to quantum chemistry and quantum computation. Although, direct laser cooling of the translational degree of freedom of molecules is still waiting for further technological or theoretical breakthroughs and ideas, many different techniques have proven to be successful in producing different types of cold as well as ultracold (i.e. T < 1 mK) molecules. In this chapter, we will concentrate on the description of one of these techniques: the photoassociation of laser cooled atoms. We will report on the status of the art of this technique for the case of cesium atoms, describing all the main experimental findings. In particular, we will illustrate the different photoassociation schemes for molecule formation, the detection schemes through photoionization, the molecule trapping in a magnetic or dipolar trap, the vibrational cooling into a single vibrational state and finally the present prospects for rotational cooling.

DOI
10.2174/978160805245511201010096

Related papers

Cold cesium molecules: from formation to cooling

A. Fioretti, Dimitris Sofikitis, R. Horchani +7 more

Recent experiments on formation of translationally cold ground state molecules, their subsequent broadband vibrational cooling and study of rotations are presented together with the related modeling. We produce cold molecules by photoassociating pairs of cold cesium atoms that can decay into ground state molecules in different vibrational levels. Then we laser cool the vibrational degree of freedom by selecting a single target vibrational level. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. Results for vibrational cooling into the v = 0, v = 1, v = 2 and v = 7 level of the singlet X 1Σ g ground electronic state are presented. Depletion spectroscopy is performed to study the rotational distribution of the created molecules. In the theoretical modeling of the process we are able to reproduce our results and investigate the prospects for a ‘complete’ cooling of molecules, including also their rotational degree of freedom.

Journal of Modern Optics•Aug 14, 2009•15 citations

Cold molecules: Formation, ro-vibrational cooling and electronic conversion

R. Horchani

The possibility of controlling all the motion as well as the internal quantum state of a sample of molecules is a long term goal in the cold molecules field. Although many different techniques have been used to produce ultra-cold molecules, in this paper, we will concentrate on the optical pumping technique successfully used to achieve rotational and vibrational cooling of Cs2molecules. We will review the different photo-association schemes for molecule formation, the detection schemes through photoionization, the ro-vibrational cooling into a single level and finally the electronic conversion. In addition, we will present a theoretical model for both ro-vibrational cooling and electronic conversion that can be used for the preparation of different experiments.

International Journal of Modern Physics B•May 31, 2016•2 citations

Photoassociative Spectroscopy and Formation of Cold Molecules

P. Pillet, Cyril Drag, B. Laburthe-Tolra +7 more

In the molecular photoassociation process, two free cold atoms absorb one photon by a resonant way, to create an excited molecule in a well defined ro-vibrational state. The photoassociative spectroscopy of alkaline dimers yields accurate determinations for the long-range parts of molecular potential curves correlated to the first s + p asymptote. In contrast to atoms, laser cooling of molecules is very difficult because of the lack of a closed two-level scheme for recycling the population. The molecular photoassociation of cold atoms opens also a promising alternative for the formation of cold ground state molecules. Photoassociation of cold cesium atoms has permitted the first observation of translationally cold ground state molecules. The case of the cesium atom is very favorable because the 0 g - and 1 u purely long-range states below the dissociation limit 6s 1/2 +6p 3/2 present Condon points at intermediate distances. Such configurations offer rather efficient channels for the creation of singlet or triplet ground state Cs 2 molecules after spontaneous decay.

Physica Scripta•Jan 1, 2000•0 citations

Cold molecules

P. van der Straten, Harold J. Metcalf

Slowing, cooling, and trapping molecules One of the major achievements in physics during the last two decades of the twentieth century was the ability to cool and trap atoms [1]. Laser cooling can produce previously inconceivable atomic temperatures of less than 1 μK. Atoms with sufficiently low kinetic energy can be trapped in magnetic and optical traps and thus studied for a prolonged time, thereby improving the resolution of spectroscopy by many orders of magnitude as well as reducing Doppler broadening. Furthermore, besides the external degrees of freedom, the internal degrees of freedom of the atoms can also be manipulated, leading to full control of the atoms. One of the holy grails of physics, the achievement of Bose–Einstein condensation in a dilute gas, was achieved mainly because of laser cooling and trapping of atoms. One of the natural extensions of laser cooling and trapping of atoms is the application of the techniques to molecules. Molecules offer a much richer internal structure than atoms, and thus provide extended possibilities to experimentalists. However, atomic laser cooling is based on the repetitive scattering of light and requires a closed, or at least nearly closed, two-level system. Because of the complicated internal structure of molecules, a closed two-level system cannot usually be found because they have many different electronic, vibrational, and rotational states and in general can decay to many different states after absorption of light (see Chap. 16). This requires a complete rethinking of the schemes that are used to cool atoms. Still, because of the extended possibilities cold molecules can offer with respect to cold atoms, there have been a large number of techniques developed to slow, cool, and trap them. These techniques can be divided into two classes, namely direct and indirect cooling. In the first case, molecules at cryogenic or room temperature are directly slowed and cooled. Although many different slowing techniques are used, this chapter focuses on Stark slowing of molecules since it was the first technique developed. Apart from the Stark shift of the molecules, the Zeeman and light shift of molecules can also be used to slow them. The idea behind Stark slowing is to subject the moving molecules to a continuously increasing electric field so that their kinetic energy is converted into potential energy.

Cambridge University Press eBooks•Dec 31, 2015•0 citations

Laser cooling of rotation and vibration by optical pumping

Isam Manai, R. Horchani, M. Hamamda +5 more

We have recently demonstrated that optical pumping methods combined with photo-association of ultra-cold atoms can produce ultra-cold and dense samples of molecules in their absolute rovibronic ground state. More generally, both the external and internal degrees of freedom can be cooled by addressing selected rovibrational levels on demand. Here, we recall the basic concepts and main steps of our experiments, including the excitation schemes and detection techniques we use to achieve the rovibrational cooling of Cs2 molecules. In addition, we present the determination of formation pathways and a theoretical analysis explaining the experimental observations. These simulations improve the spectroscopic knowledge required to transfer molecules to any desired rovibrational level.

arXiv:1306.3461•Molecular Physics•Jun 14, 2013•11 citations

Formation of cold Cs[sub 2] molecules through photoassociation

A. Fioretti

We report on the formation of translationally cold Cs2 ground-state molecules through photoassociation of laser-cooled cesium atoms in a magneto-optical trap. The cold molecules are obtained after spontaneous decay of photoassociated molecules, and detected after pulsed-laser photoionization into Cs2+ ions. Photoassociation spectra of cesium attractive molecular states below the 6S1/2+6P3/2 dissociation limits are reported, obtained with both ion detection and trap-loss method. A temperature as low as 20−5+15 has been measured for the molecular cloud.

AIP conference proceedings•Jan 1, 2000•7 citations
The cold-molecule field concerns the physics and the applications of molecular systems with translational temperature well below the 1 К range. The possibility of controlling all the motion as well as the internal quantum state of a sample of molecules is a long-term goal that opens the possibility for many new experiments and measurements ranging from fundamental constants to quantum chemistry and quantum computation. Although, direct laser cooling of the translational degree of freedom of molecules is still waiting for further technological or theoretical breakthroughs and ideas, many different techniques have proven to be successful in producing different types of cold as well as ultracold (i.e. T < 1 mK) molecules. In this chapter, we will concentrate on the description of one of these techniques: the photoassociation of laser cooled atoms. We will report on the status of the art of this technique for the case of cesium atoms, describing all the main experimental findings. In particular, we will illustrate the different photoassociation schemes for molecule formation, the detection schemes through photoionization, the molecule trapping in a magnetic or dipolar trap, the vibrational cooling into a single vibrational state and finally the present prospects for rotational cooling.
Recent experiments on formation of translationally cold ground state molecules, their subsequent broadband vibrational cooling and study of rotations are presented together with the related modeling. We produce cold molecules by photoassociating pairs of cold cesium atoms that can decay into ground state molecules in different vibrational levels. Then we laser cool the vibrational degree of freedom by selecting a single target vibrational level. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. Results for vibrational cooling into the v = 0, v = 1, v = 2 and v = 7 level of the singlet X 1Σ g ground electronic state are presented. Depletion spectroscopy is performed to study the rotational distribution of the created molecules. In the theoretical modeling of the process we are able to reproduce our results and investigate the prospects for a ‘complete’ cooling of molecules, including also their rotational degree of freedom.
The possibility of controlling all the motion as well as the internal quantum state of a sample of molecules is a long term goal in the cold molecules field. Although many different techniques have been used to produce ultra-cold molecules, in this paper, we will concentrate on the optical pumping technique successfully used to achieve rotational and vibrational cooling of Cs2molecules. We will review the different photo-association schemes for molecule formation, the detection schemes through photoionization, the ro-vibrational cooling into a single level and finally the electronic conversion. In addition, we will present a theoretical model for both ro-vibrational cooling and electronic conversion that can be used for the preparation of different experiments.
In the molecular photoassociation process, two free cold atoms absorb one photon by a resonant way, to create an excited molecule in a well defined ro-vibrational state. The photoassociative spectroscopy of alkaline dimers yields accurate determinations for the long-range parts of molecular potential curves correlated to the first s + p asymptote. In contrast to atoms, laser cooling of molecules is very difficult because of the lack of a closed two-level scheme for recycling the population. The molecular photoassociation of cold atoms opens also a promising alternative for the formation of cold ground state molecules. Photoassociation of cold cesium atoms has permitted the first observation of translationally cold ground state molecules. The case of the cesium atom is very favorable because the 0 g - and 1 u purely long-range states below the dissociation limit 6s 1/2 +6p 3/2 present Condon points at intermediate distances. Such configurations offer rather efficient channels for the creation of singlet or triplet ground state Cs 2 molecules after spontaneous decay.
Slowing, cooling, and trapping molecules One of the major achievements in physics during the last two decades of the twentieth century was the ability to cool and trap atoms [1]. Laser cooling can produce previously inconceivable atomic temperatures of less than 1 μK. Atoms with sufficiently low kinetic energy can be trapped in magnetic and optical traps and thus studied for a prolonged time, thereby improving the resolution of spectroscopy by many orders of magnitude as well as reducing Doppler broadening. Furthermore, besides the external degrees of freedom, the internal degrees of freedom of the atoms can also be manipulated, leading to full control of the atoms. One of the holy grails of physics, the achievement of Bose–Einstein condensation in a dilute gas, was achieved mainly because of laser cooling and trapping of atoms. One of the natural extensions of laser cooling and trapping of atoms is the application of the techniques to molecules. Molecules offer a much richer internal structure than atoms, and thus provide extended possibilities to experimentalists. However, atomic laser cooling is based on the repetitive scattering of light and requires a closed, or at least nearly closed, two-level system. Because of the complicated internal structure of molecules, a closed two-level system cannot usually be found because they have many different electronic, vibrational, and rotational states and in general can decay to many different states after absorption of light (see Chap. 16). This requires a complete rethinking of the schemes that are used to cool atoms. Still, because of the extended possibilities cold molecules can offer with respect to cold atoms, there have been a large number of techniques developed to slow, cool, and trap them. These techniques can be divided into two classes, namely direct and indirect cooling. In the first case, molecules at cryogenic or room temperature are directly slowed and cooled. Although many different slowing techniques are used, this chapter focuses on Stark slowing of molecules since it was the first technique developed. Apart from the Stark shift of the molecules, the Zeeman and light shift of molecules can also be used to slow them. The idea behind Stark slowing is to subject the moving molecules to a continuously increasing electric field so that their kinetic energy is converted into potential energy.
We have recently demonstrated that optical pumping methods combined with photo-association of ultra-cold atoms can produce ultra-cold and dense samples of molecules in their absolute rovibronic ground state. More generally, both the external and internal degrees of freedom can be cooled by addressing selected rovibrational levels on demand. Here, we recall the basic concepts and main steps of our experiments, including the excitation schemes and detection techniques we use to achieve the rovibrational cooling of Cs2 molecules. In addition, we present the determination of formation pathways and a theoretical analysis explaining the experimental observations. These simulations improve the spectroscopic knowledge required to transfer molecules to any desired rovibrational level.
We report on the formation of translationally cold Cs2 ground-state molecules through photoassociation of laser-cooled cesium atoms in a magneto-optical trap. The cold molecules are obtained after spontaneous decay of photoassociated molecules, and detected after pulsed-laser photoionization into Cs2+ ions. Photoassociation spectra of cesium attractive molecular states below the 6S1/2+6P3/2 dissociation limits are reported, obtained with both ion detection and trap-loss method. A temperature as low as 20−5+15 has been measured for the molecular cloud.