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

The Journal of Physical Chemistry Letters

Mechanistic Insights into Ultracold Chemical Reactions under the Control of the Geometric Phase

Jiayu Huang, Brian K. Kendrick, Dong Hui Zhang

Published Feb 24, 2021• 20 citations
Publisher

Abstract

Ultracold chemical reactions involve collision temperatures approaching absolute zero, and for molecular systems that exhibit a barrierless and exoergic reaction path significant reactivity can occur. In addition, many molecules contain a conical intersection, and the associated geometric phase has been shown to significantly alter the outcome of ultracold reactions. Here we report a quantum dynamics study for the ultracold O + OH → H + O 2 reaction. An analysis of the scattering wave functions reveals explicitly the nature of the quantum interference between the direct and looping reaction pathways around the conical intersection and thus illustrates how the reaction proceeds under the control of the geometric phase for the first time. The wave function analysis should generalize to other ultracold reactions that contain a conical intersection. Our findings indicate that quantum control techniques such as an optical lattice trap or the initial state orientation may be effective in controlling the reactivity.

DOI
10.1021/acs.jpclett.1c00133

Related papers

The geometric phase controls ultracold chemistry

Brian K. Kendrick, Jisha Hazra, N. Balakrishnan

The geometric phase is shown to control the outcome of an ultracold chemical reaction. The control is a direct consequence of the sign change on the interference term between two scattering pathways (direct and looping), which contribute to the reactive collision process in the presence of a conical intersection (point of degeneracy between two Born-Oppenheimer electronic potential energy surfaces). The unique properties of the ultracold energy regime lead to an effective quantization of the scattering phase shift enabling maximum constructive or destructive interference between the two pathways. By taking the O+OH→H+O2 reaction as an illustrative example, it is shown that inclusion of the geometric phase modifies ultracold reaction rates by nearly two orders of magnitude. Interesting experimental control possibilities include the application of external electric and magnetic fields that might be used to exploit the geometric phase effect reported here and experimentally switch on or off the reactivity.

Nature Communications•Jul 30, 2015•95 citations

Importance of Geometric Phase Effects in Ultracold Chemistry

Jisha Hazra, Brian K. Kendrick, N. Balakrishnan

It is demonstrated that the inclusion of the geometric phase has an important effect on ultracold chemical reaction rates. The effect appears in rotationally and vibrationally resolved integral cross sections as well as cross sections summed over all product quantum states. The effect arises from interference between scattering amplitudes of two reaction pathways: a direct path and a looping path that encircle the conical intersection between the two lowest adiabatic electronic potential energy surfaces. It is magnified when the two scattering amplitudes have comparable magnitude and they scatter into the same angular region which occurs in the isotropic scattering characteristic of the ultracold regime (s-wave scattering). Results are presented for the O + OH → H + O2 reaction for total angular momentum quantum number J = 0-5. Large geometric phase effects occur for collision energies below 0.1 K, but the effect vanishes at higher energies when contributions from different partial waves are included. It is also qualitatively demonstrated that the geometric phase effect can be modulated by applying an external electric field allowing the possibility of quantum control of chemical reactions in the ultracold regime. In this case, the geometric phase plays the role of a "quantum switch" which can turn the reaction "on" or "off".

The Journal of Physical Chemistry A•Aug 28, 2015•25 citations

Geometric Phase Effects in Ultracold Chemical Reactions

Brian K. Kendrick, N. Balakrishnan

The role of the geometric phase effect in chemical reaction dynamics has long been a topic of active experimental and theoretical investigations. The topic has received renewed interest in recent years in cold and ultracold chemistry where it was shown to play a decisive role in state-to-state chemical dynamics. We provide a brief review of these developments focusing on recent studies of O + OH and hydrogen exchange in the H + H 2 and D + HD reactions at cold and ultracold temperatures. Non-adiabatic effects in ultracold chemical dynamics arising from the conical intersection between two electronic potential energy surfaces are also briefly discussed. By taking the hydrogen exchange reaction as an illustrative example it is shown that the inclusion of the geometric phase effect captures the essential features of non-adiabatic dynamics at collision energies below the conical intersection.

Atoms•Jul 3, 2019•9 citations

Non-adiabatic quantum interference effects and chaoticity in the ultracold Li + LiNa $\to$ Li$_2$ + Na reaction

Brian K. Kendrick, Hui Li, Li, Ming +3 more

Electronically non-adiabatic effects play an important role in many chemical reactions. How these effects manifest in cold and ultracold chemistry remain largely unexplored. Here, through first principles non-adiabatic quantum dynamics calculations of the Li + LiNa $\to$ Li$_2$ + Na chemical reaction, it is shown that non-adiabatic dynamics induces quantum interference effects that dramatically alter the ultracold rotationally resolved reaction rate coefficients. The interference effect arises from a conical intersection between the ground and an excited electronic state that is energetically accessible even for ultracold collisions. These unique interference effects might be exploited for quantum control applications as a quantum molecular switch. A statistical analysis of rotational populations of the Li$_2$ product reveals a Poisson distribution implying an underlying classically chaotic dynamics. The Poisson distribution is robust and amenable to experimental verification and appears to be a universal property of ultracold reactions involving alkali metal dimers.

arXiv:2006.15238•APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts•Jun 26, 2020•1 citation

Photodissociation of a diatomic molecule in the quantum regime reveals ultracold chemistry

Mickey McDonald, B. H. McGuyer, Fabian A. C. Apfelbeck +4 more

Chemical reactions at temperatures near absolute zero require a full quantum description of the reaction pathways and enable enhanced control of the products via quantum state selection. Ultracold molecule experiments have provided initial insight into the quantum nature of basic chemical processes involving diatomic molecules, for example from studies of bimolecular reactions, but complete control over the reactants and products has remained elusive. The half-collision process of photodissociation is an indispensable tool in molecular physics and offers significantly more control than the reverse process of photoassociation. Here we reach a fully quantum regime with photodissociation of ultracold $^{88}$Sr$_2$ molecules where the initial bound state of the molecule and the target continuum state of the fragments are strictly controlled. Detection of the photodissociation products via optical absorption imaging reveals the hallmarks of ultracold chemistry: resonant and nonresonant barrier tunneling, importance of quantum statistics, presence of forbidden reaction pathways, and matter wave interference of reaction products. In particular, this interference yields fragment angular distributions with a strong breaking of cylindrical symmetry, so far unobserved in photodissociation. We definitively show that the quasiclassical description of photodissociation fails in the ultracold regime. Instead, a quantum model accurately reproduces our results and yields new intuition.

•Dec 21, 2015•0 citations

Non-adiabatic quantum interference in the ultracold Li + LiNa → Li 2 + Na reaction

Brian K. Kendrick, Hui Li, Ming Li +3 more

Electronically non-adiabatic effects play an important role in many chemical reactions. However, how these effects manifest in cold and ultracold chemistry remains largely unexplored. Here for the first time we present from first principles the non-adiabatic quantum dynamics of the reactive scattering between ultracold alkali-metal LiNa molecules and Li atoms. We show that non-adiabatic dynamics induces quantum interference effects that dramatically alter the ultracold rotationally resolved reaction rate coefficients. The interference effect arises from the conical intersection between the ground and an excited electronic state that is energetically accessible even for ultracold collisions. These unique interference effects might be exploited for quantum control applications such as a quantum molecular switch. The non-adiabatic dynamics are based on full-dimensional ab initio potential energy surfaces for the two electronic states that includes the non-adiabatic couplings and an accurate treatment of the long-range interactions. A statistical analysis of rotational populations of the Li2 product reveals a Poisson distribution implying the underlying classical dynamics are chaotic. The Poisson distribution is robust and amenable to experimental verification and appears to be a universal property of ultracold reactions involving alkali metal dimers.

Physical Chemistry Chemical Physics•Jan 1, 2021•48 citations
Ultracold chemical reactions involve collision temperatures approaching absolute zero, and for molecular systems that exhibit a barrierless and exoergic reaction path significant reactivity can occur. In addition, many molecules contain a conical intersection, and the associated geometric phase has been shown to significantly alter the outcome of ultracold reactions. Here we report a quantum dynamics study for the ultracold O + OH → H + O 2 reaction. An analysis of the scattering wave functions reveals explicitly the nature of the quantum interference between the direct and looping reaction pathways around the conical intersection and thus illustrates how the reaction proceeds under the control of the geometric phase for the first time. The wave function analysis should generalize to other ultracold reactions that contain a conical intersection. Our findings indicate that quantum control techniques such as an optical lattice trap or the initial state orientation may be effective in controlling the reactivity.
The geometric phase is shown to control the outcome of an ultracold chemical reaction. The control is a direct consequence of the sign change on the interference term between two scattering pathways (direct and looping), which contribute to the reactive collision process in the presence of a conical intersection (point of degeneracy between two Born-Oppenheimer electronic potential energy surfaces). The unique properties of the ultracold energy regime lead to an effective quantization of the scattering phase shift enabling maximum constructive or destructive interference between the two pathways. By taking the O+OH→H+O2 reaction as an illustrative example, it is shown that inclusion of the geometric phase modifies ultracold reaction rates by nearly two orders of magnitude. Interesting experimental control possibilities include the application of external electric and magnetic fields that might be used to exploit the geometric phase effect reported here and experimentally switch on or off the reactivity.
It is demonstrated that the inclusion of the geometric phase has an important effect on ultracold chemical reaction rates. The effect appears in rotationally and vibrationally resolved integral cross sections as well as cross sections summed over all product quantum states. The effect arises from interference between scattering amplitudes of two reaction pathways: a direct path and a looping path that encircle the conical intersection between the two lowest adiabatic electronic potential energy surfaces. It is magnified when the two scattering amplitudes have comparable magnitude and they scatter into the same angular region which occurs in the isotropic scattering characteristic of the ultracold regime (s-wave scattering). Results are presented for the O + OH → H + O2 reaction for total angular momentum quantum number J = 0-5. Large geometric phase effects occur for collision energies below 0.1 K, but the effect vanishes at higher energies when contributions from different partial waves are included. It is also qualitatively demonstrated that the geometric phase effect can be modulated by applying an external electric field allowing the possibility of quantum control of chemical reactions in the ultracold regime. In this case, the geometric phase plays the role of a "quantum switch" which can turn the reaction "on" or "off".
The role of the geometric phase effect in chemical reaction dynamics has long been a topic of active experimental and theoretical investigations. The topic has received renewed interest in recent years in cold and ultracold chemistry where it was shown to play a decisive role in state-to-state chemical dynamics. We provide a brief review of these developments focusing on recent studies of O + OH and hydrogen exchange in the H + H 2 and D + HD reactions at cold and ultracold temperatures. Non-adiabatic effects in ultracold chemical dynamics arising from the conical intersection between two electronic potential energy surfaces are also briefly discussed. By taking the hydrogen exchange reaction as an illustrative example it is shown that the inclusion of the geometric phase effect captures the essential features of non-adiabatic dynamics at collision energies below the conical intersection.
Non-adiabatic quantum interference effects and chaoticity in the ultracold Li + LiNa →\to→ Li2_22​ + Na reaction
Electronically non-adiabatic effects play an important role in many chemical reactions. How these effects manifest in cold and ultracold chemistry remain largely unexplored. Here, through first principles non-adiabatic quantum dynamics calculations of the Li + LiNa →\to→ Li2_22​ + Na chemical reaction, it is shown that non-adiabatic dynamics induces quantum interference effects that dramatically alter the ultracold rotationally resolved reaction rate coefficients. The interference effect arises from a conical intersection between the ground and an excited electronic state that is energetically accessible even for ultracold collisions. These unique interference effects might be exploited for quantum control applications as a quantum molecular switch. A statistical analysis of rotational populations of the Li2_22​ product reveals a Poisson distribution implying an underlying classically chaotic dynamics. The Poisson distribution is robust and amenable to experimental verification and appears to be a universal property of ultracold reactions involving alkali metal dimers.
Chemical reactions at temperatures near absolute zero require a full quantum description of the reaction pathways and enable enhanced control of the products via quantum state selection. Ultracold molecule experiments have provided initial insight into the quantum nature of basic chemical processes involving diatomic molecules, for example from studies of bimolecular reactions, but complete control over the reactants and products has remained elusive. The half-collision process of photodissociation is an indispensable tool in molecular physics and offers significantly more control than the reverse process of photoassociation. Here we reach a fully quantum regime with photodissociation of ultracold 88^{88}88Sr2_22​ molecules where the initial bound state of the molecule and the target continuum state of the fragments are strictly controlled. Detection of the photodissociation products via optical absorption imaging reveals the hallmarks of ultracold chemistry: resonant and nonresonant barrier tunneling, importance of quantum statistics, presence of forbidden reaction pathways, and matter wave interference of reaction products. In particular, this interference yields fragment angular distributions with a strong breaking of cylindrical symmetry, so far unobserved in photodissociation. We definitively show that the quasiclassical description of photodissociation fails in the ultracold regime. Instead, a quantum model accurately reproduces our results and yields new intuition.
Electronically non-adiabatic effects play an important role in many chemical reactions. However, how these effects manifest in cold and ultracold chemistry remains largely unexplored. Here for the first time we present from first principles the non-adiabatic quantum dynamics of the reactive scattering between ultracold alkali-metal LiNa molecules and Li atoms. We show that non-adiabatic dynamics induces quantum interference effects that dramatically alter the ultracold rotationally resolved reaction rate coefficients. The interference effect arises from the conical intersection between the ground and an excited electronic state that is energetically accessible even for ultracold collisions. These unique interference effects might be exploited for quantum control applications such as a quantum molecular switch. The non-adiabatic dynamics are based on full-dimensional ab initio potential energy surfaces for the two electronic states that includes the non-adiabatic couplings and an accurate treatment of the long-range interactions. A statistical analysis of rotational populations of the Li2 product reveals a Poisson distribution implying the underlying classical dynamics are chaotic. The Poisson distribution is robust and amenable to experimental verification and appears to be a universal property of ultracold reactions involving alkali metal dimers.