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Bulletin of the American Physical Society

Ultracold Long-Range Rydberg Molecules with Complex Multichannel Spectra

Matthew T. Eiles, Chris H. Greene

Published May 27, 2016• 0 citations
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Abstract

A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound trilobite molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation.

Related papers

Ultracold Long-Range Rydberg Molecules with Complex Multichannel Spectra

Matthew T. Eiles, Chris H. Greene

A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound "trilobite" molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation.

arXiv:1507.03616•Physical Review Letters•Nov 3, 2015•25 citations

How do ultralong-range homonuclear Rydberg molecules get their permanent dipole moments?

H. R. Sadeghpour, Seth T. Rittenhouse

Cold and ultracold Rydberg atoms are in considerable vogue for their ability to creating strong interactions, stemming from their exaggerated and readily tunable properties. Ultralong-range Rydberg molecules have been predicted to form from the interaction of ultracold Rydberg atoms with ground-state atoms and polar molecules. In this work, we discuss and demonstrate how such molecules, which are homonuclear, form substantially large permanent electric dipole moments. A corollary benefit of such strong hybridisation is the realisation of high angular momentum degenerate Rydberg molecules (so-called trilobite molecules) with standard photoassociation techniques.

Molecular Physics•Jun 28, 2013•12 citations

Ultra-long range, ultracold polar and non-polar Rydberg molecules

Chris H. Greene, A S Dickinson, H. R. Sadeghpour

Summary form only given. The discovery of ultracold and dilute ensembles of atoms and molecules in magneto-optical traps (MOT) and in atomic Bose-Einstein condensates (BECs) has ushered in a new era of precision atomic and molecular spectroscopy. Since the atoms in such cold environments predominantly interact via long-range forces, the creation of BECs and dilute atomic samples has made the study of very long-range molecular states possible. In this work (Greene et al, Phys. Rev. Lett. vol. 85, p. 2458, 2000), we discuss a particular interatomic arrangement that should be favored in modern-day MOT and BEC setups and should result in the production of molecular Rydberg states whose vibrational wave functions are localized at internuclear distances of order n/sup 2/ Bohr radii, where n is the principal quantum number. The vibrational binding energies of these molecules for n=20-50 fall in the MHz and GHz range, for molecules excited from /sup 87/Rb ultracold atomic gas. We predict two distinct classes of molecular Rydberg states. The nonpolar class of Rydberg molecules form from the interaction between a Rb(nl/sub j/) Rydberg atom with low orbital angular momentum l/sub j//spl les/2 and a distant Rb ground state atom. Rydberg molecules of the second class form from the interaction between an excited Rb atom in high (l/sub j/>2) orbital angular momentum states with a ground state Rb atom.

Quantum Electronics and Laser Science Conference•Nov 13, 2002•0 citations

Ultralong-range Rydberg molecules of Hg atoms

Agata Wojciechowska, Michał Tomza, Matthew T. Eiles

Ultralong-range Rydberg molecules, composed of an excited Rydberg atom and a ground-state atom, are characterized by large bond lengths, dipole moments, sensitivity to external fields, and an unusual binding mechanism based on low-energy elastic electron scattering. Although Rydberg molecules formed between alkali atoms have received the most attention, the additional complexity found in atoms with more than a single valence electron poses new theoretical challenges as well as new possibilities for control and design of the molecular structure. In this paper, we extend the theory of Rydberg molecules to include the additional spin coupling of the Rydberg states of a multivalent atom. We employ this theory to describe the properties of Rydberg molecules composed of mercury atoms. We calculate the potential energy curves of both heteronuclear (${\mathrm{Hg}}^{*}\mathrm{Rb}$) and homonuclear (${\mathrm{Hg}}^{*}\mathrm{Hg}$) molecules. In the former case, we propose the realization of long-range spin entanglement and remote spin flip. In the latter, we show how long-lived metastable molecular states of ${\mathrm{Hg}}^{*}\mathrm{Hg}$ exist as resonances above the dissociation threshold.

arXiv:2412.05025•Physical Review A•Apr 14, 2025•4 citations

Ultra-cold long-range Rydberg-ground molecules

Suying Bai, Jingxu Bai, Xiaoxuan Han +2 more

Ultra-cold long-range Rydberg-ground molecule consisting of a Rydberg atom and one or more ground-state atoms is formed by low-energy scattering between the Rydberg electron and ground-state atoms located inside the Rydberg electron’s wave function. The low-energy scattering interaction, initially investigated by Fermi and Omont, has been predicted to lead to molecular binding in a novel type of Rydberg molecules, including the trilobite and butterfly molecules. Their unconventional binding mechanism, which is unlike covalent, or ionic, or van der Waals bonds, results in loosely bound molecules with bond lengths on the order of thousands of Bohr radius. This kind of molecule with large size and huge permanent electric dipole moment is a good candidate for realizing the certain strongly correlated many-body gases and for quantum information processing, as well as for dipolar quantum gases and spin systems with long-range interactions. Consequently, these molecules have received considerable attention in recent years. In this paper, we review the recent theoretical and experimental investigations of ultra-cold long-range Rydberg-ground molecules, including the scattering interaction between the Rydberg electron and ground-state atom and the resulting adiabatic potential curves, experimental observations of photo-associated Rydberg-ground molecules spectra, as well as the measurements of permanent electric dipole moment. Ultra-cold long-range Rydberg-ground molecules are prepared by photoassociation in a high-density cold atom sample. Therefore, the Rydberg electron can bind several ground-state atoms to form a polyatomic Rydberg-ground molecule. The permanent molecular electric-dipole moments are revealed by spectral line broadening in the electric fields. The latest research pointed out that the permanent electric dipole moments of the Cs nDJ -type Rydberg-ground molecules are negative, which is different from the previous reports (the electric dipole moments are positive). The negative sign reflects a deficiency of Rydberg-electron density near the ground-state perturber, which is caused by electronic configuration mixing.

Acta Physica Sinica•Jan 1, 2021•0 citations

Charged ultralong-range Rydberg trimers

Daniel J. Bosworth, Frederic Hummel, Peter Schmelcher

We show that the recently observed class of long-range ion-Rydberg molecules can be divided into two families of states, which are characterized by their unique electronic structures resulting from the ion-induced admixture of quantum defect-split Rydberg $nP$ states with different low-field-seeking high-$l$ states. We predict that in both cases, these diatomic molecular states can bind additional ground-state atoms lying within the orbit of the Rydberg electron, thereby forming charged ultralong-range Rydberg molecules (ULRMs) with binding energies similar to that of conventional nonpolar ULRMs. To demonstrate this, we consider a Rydberg atom interacting with a single ground-state atom and an ion. The additional atom breaks the system's cylindrical symmetry, which leads to mixing between states that would otherwise be decoupled. The electronic structure is obtained using exact diagonalization over a finite basis and the vibrational structure is determined using the multiconfiguration time-dependent Hartree method. Due to the lobelike structure of the electronic density, bound trimers with both linear and nonlinear geometrical configurations of the three nuclei are possible. The predicted trimer binding energies and excitation series are distinct enough from those of the ion-Rydberg dimer to be observed using current experimental techniques.

arXiv:2211.13643•Physical Review A•Feb 9, 2023•7 citations
A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound trilobite molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation.
A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound "trilobite" molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation.
Cold and ultracold Rydberg atoms are in considerable vogue for their ability to creating strong interactions, stemming from their exaggerated and readily tunable properties. Ultralong-range Rydberg molecules have been predicted to form from the interaction of ultracold Rydberg atoms with ground-state atoms and polar molecules. In this work, we discuss and demonstrate how such molecules, which are homonuclear, form substantially large permanent electric dipole moments. A corollary benefit of such strong hybridisation is the realisation of high angular momentum degenerate Rydberg molecules (so-called trilobite molecules) with standard photoassociation techniques.
Summary form only given. The discovery of ultracold and dilute ensembles of atoms and molecules in magneto-optical traps (MOT) and in atomic Bose-Einstein condensates (BECs) has ushered in a new era of precision atomic and molecular spectroscopy. Since the atoms in such cold environments predominantly interact via long-range forces, the creation of BECs and dilute atomic samples has made the study of very long-range molecular states possible. In this work (Greene et al, Phys. Rev. Lett. vol. 85, p. 2458, 2000), we discuss a particular interatomic arrangement that should be favored in modern-day MOT and BEC setups and should result in the production of molecular Rydberg states whose vibrational wave functions are localized at internuclear distances of order n/sup 2/ Bohr radii, where n is the principal quantum number. The vibrational binding energies of these molecules for n=20-50 fall in the MHz and GHz range, for molecules excited from /sup 87/Rb ultracold atomic gas. We predict two distinct classes of molecular Rydberg states. The nonpolar class of Rydberg molecules form from the interaction between a Rb(nl/sub j/) Rydberg atom with low orbital angular momentum l/sub j//spl les/2 and a distant Rb ground state atom. Rydberg molecules of the second class form from the interaction between an excited Rb atom in high (l/sub j/>2) orbital angular momentum states with a ground state Rb atom.
Ultralong-range Rydberg molecules, composed of an excited Rydberg atom and a ground-state atom, are characterized by large bond lengths, dipole moments, sensitivity to external fields, and an unusual binding mechanism based on low-energy elastic electron scattering. Although Rydberg molecules formed between alkali atoms have received the most attention, the additional complexity found in atoms with more than a single valence electron poses new theoretical challenges as well as new possibilities for control and design of the molecular structure. In this paper, we extend the theory of Rydberg molecules to include the additional spin coupling of the Rydberg states of a multivalent atom. We employ this theory to describe the properties of Rydberg molecules composed of mercury atoms. We calculate the potential energy curves of both heteronuclear (Hg∗Rb{\mathrm{Hg}}^{*}\mathrm{Rb}Hg∗Rb) and homonuclear (Hg∗Hg{\mathrm{Hg}}^{*}\mathrm{Hg}Hg∗Hg) molecules. In the former case, we propose the realization of long-range spin entanglement and remote spin flip. In the latter, we show how long-lived metastable molecular states of Hg∗Hg{\mathrm{Hg}}^{*}\mathrm{Hg}Hg∗Hg exist as resonances above the dissociation threshold.
Ultra-cold long-range Rydberg-ground molecule consisting of a Rydberg atom and one or more ground-state atoms is formed by low-energy scattering between the Rydberg electron and ground-state atoms located inside the Rydberg electron’s wave function. The low-energy scattering interaction, initially investigated by Fermi and Omont, has been predicted to lead to molecular binding in a novel type of Rydberg molecules, including the trilobite and butterfly molecules. Their unconventional binding mechanism, which is unlike covalent, or ionic, or van der Waals bonds, results in loosely bound molecules with bond lengths on the order of thousands of Bohr radius. This kind of molecule with large size and huge permanent electric dipole moment is a good candidate for realizing the certain strongly correlated many-body gases and for quantum information processing, as well as for dipolar quantum gases and spin systems with long-range interactions. Consequently, these molecules have received considerable attention in recent years. In this paper, we review the recent theoretical and experimental investigations of ultra-cold long-range Rydberg-ground molecules, including the scattering interaction between the Rydberg electron and ground-state atom and the resulting adiabatic potential curves, experimental observations of photo-associated Rydberg-ground molecules spectra, as well as the measurements of permanent electric dipole moment. Ultra-cold long-range Rydberg-ground molecules are prepared by photoassociation in a high-density cold atom sample. Therefore, the Rydberg electron can bind several ground-state atoms to form a polyatomic Rydberg-ground molecule. The permanent molecular electric-dipole moments are revealed by spectral line broadening in the electric fields. The latest research pointed out that the permanent electric dipole moments of the Cs nDJ -type Rydberg-ground molecules are negative, which is different from the previous reports (the electric dipole moments are positive). The negative sign reflects a deficiency of Rydberg-electron density near the ground-state perturber, which is caused by electronic configuration mixing.
We show that the recently observed class of long-range ion-Rydberg molecules can be divided into two families of states, which are characterized by their unique electronic structures resulting from the ion-induced admixture of quantum defect-split Rydberg nPnPnP states with different low-field-seeking high-lll states. We predict that in both cases, these diatomic molecular states can bind additional ground-state atoms lying within the orbit of the Rydberg electron, thereby forming charged ultralong-range Rydberg molecules (ULRMs) with binding energies similar to that of conventional nonpolar ULRMs. To demonstrate this, we consider a Rydberg atom interacting with a single ground-state atom and an ion. The additional atom breaks the system's cylindrical symmetry, which leads to mixing between states that would otherwise be decoupled. The electronic structure is obtained using exact diagonalization over a finite basis and the vibrational structure is determined using the multiconfiguration time-dependent Hartree method. Due to the lobelike structure of the electronic density, bound trimers with both linear and nonlinear geometrical configurations of the three nuclei are possible. The predicted trimer binding energies and excitation series are distinct enough from those of the ion-Rydberg dimer to be observed using current experimental techniques.