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

Acta Physica Sinica

Adiabatic conversion of ultracold atoms into molecules via square-shaped pulse field

Yan Qin, Sheng-Chang Li

Published Jan 1, 2018• 0 citations
Publisher

Abstract

On the basis of the stimulated Raman adiabatic passage technology, we study the conversion of ultracold atoms into diatomic molecules by using a square-shaped pulse field. By the method of adiabatic fidelity, we analyze the dynamical evolution process of the coherent population trapping state for the atom-molecule conversion system. We introduce two adiabatic fidelities to describe the efficiency of ultracold atom-molecule conversion, i.e.:1) the final adiabatic fidelity, which gives the value of the adiabatic fidelity at the end of the evolution:the closer to 1 it is, the higher the conversion efficiency is; 2) the final maximum adiabatic fidelity, which denotes the maximum value that can be achieved at the end of evolution, indicating the highest conversion efficiency. With these two quantities, we discuss how to achieve higher adiabatic fidelity for the coherent population trapping state through optimizing the pulse-delay time and the pulse-laser intensity of the stimulated Raman adiabatic passage. In addition, we also discuss the effects of the width of pulses on the ultracold atom-molecule conversion efficiency and the feasibility of continuous light. It is shown that the final adiabatic fidelity of the coherent population trapping state demonstrates a large periodic oscillation with the pulse-laser intensity. By calculating and analyzing the final adiabatic fidelity and the final maximum adiabatic fidelity, we obtain the conditions for higher efficiency conversion, which gives the best choice of the pulse-laser intensity, the pulse-delay time, and the width of pulses. The results show that the scheme of square-shaped pulses we discussed has obvious advantages compared with that of Gaussian-shaped pulses, which can achieve high adiabatic fidelity and realize higher ultracold atom-molecule conversion efficiency via employing the pulse-laser field with low intensity. Further detailed comparison between the square-shaped pulses and the Gaussian-shaped pulses is also given. Particularly, we find that the final adiabatic fidelity shows a periodic oscillation with the pulse width, which means that the high efficiency atom-molecule conversion can be achieved by using a pulse field with small width. Moreover, we find that the high efficiency conversion can also be achieved by using special continuous light under certain conditions.

DOI
10.7498/aps.67.20180908

Related papers

Adiabatic fidelity for atom-dimer conversion system in stimulated Raman adiabatic passage

Shao-Ying Meng, Wu Wei, (1)辽宁大学物理学院,沈阳 110036; (2)中国工程物理研究院北京研究生部,北京 100088；辽宁大学物理学院,沈阳 110036

From the non-U（1） invariance of the atom-dimer conversion system, we generalized the definition of fidelity to this nonlinear system. By making use of the adiabatic fidelity, we investigated the dynamics and adiabaticity of the atom-dimer conversion system in a stimulated Raman adiabatic passage （STIRAP）. We found that the adiabatic fidelity for the coherent population trapping state or dark state, as the function of the adiabatic parameter, approaches to unity following a power law. The power exponent, however, is much smaller than that predicted by the linear adiabatic theorem. We further discuss how to achieve higher adiabatic fidelity for the dark state through optimizing the external parameters of STIRAP and hence to optimize the adiabaticity of the system and obtain high conversion efficiency.

Acta Physica Sinica•Jan 1, 2009•11 citations

Atom-to-molecule conversion efficiency and adiabatic fidelity

Li-Hua Lü, You‐Quan Li

The efficiency of converting two-species fermionic atoms into bosonic molecules is investigated in terms of mean-field Lagrangian density. We find that the stimulated Raman adiabatic passage technique aided by Feshbach resonance is more effective than the bare Feshbach resonance for $^{6}\text{L}\text{i}$ atoms rather than $^{40}\text{K}$ atoms. We also generally consider the symmetry and its relevant conservation law, which enables us to introduce a natural definition of adiabatic fidelity for a coherent population trapping state. The calculated values of the fidelity are presented and then we provide an explanation of why the conversion efficiencies for $^{40}\text{K}$ and $^{6}\text{L}\text{i}$ are distinctly different.

arXiv:0803.1297•Physical Review A•May 20, 2008•24 citations

Nonlinear effect of cold Cs2 molecular conversion from ultracold atoms in a tunneling four-level structure

Yuan Liu, Junping Lan, JinHong Li +2 more

Due to the inevitability of nonlinear collisions between particles in ultracold atomic condensate experiments, it is of great significance to study the nonlinear effect for producing ultracold molecules from atomic condensates. In this work, we investigate theoretically the nonlinear effect induced by the two-body collision for producing ultracold Cs2 molecules from ultracold atoms by the stimulated Raman adiabatic passage in a tunneling four-level structure. Under the two-photon resonance condition and the coherent population trapping state, the conversion efficiency is influenced significantly by the nonlinear parameter. Meanwhile, the optimized parameter ranges of the resonance tunneling strength at the unstable excited molecular states, the effective Rabi frequencies of the two-laser fields, and the detuning of the pump field for different nonlinear parameters are suggested to obtain the high conversion efficiency of Cs2 molecules at the ground state. Finally, a maximum conversion efficiency of up to 88.56% can be realized in the optimized parameter ranges.

Canadian Journal of Physics•Aug 3, 2020•0 citations

Effects of external field parameters on conversion from ultracold atoms to heteronuclear triatomic molecules

Guan-Qiang Li, Peng Ping

We investigate the effects of external field parameters, including the strength of Rabi pulse, its width, and single-photon detuning, on conversion from ultracold atoms to heteronuclear triatomic molecules by two-photon stimulated Raman adiabatic passage. It is found that the conversion efficiency of the system decreases first with the strength of the Stokes pulse increasing, then oscillates, and finally approaches a stable value, which is less than 1. But for the pump pulse, the efficiency first increases with the increase of the pulse intensity, and then approaches 1 quickly. The results show that the two pulses play different roles in the conversion. The pulse width can not only determine the final conversion efficiency, but also be used to reflect the time needed for stable conversion. The system has a higher efficiency of conversion for red detuning pump laser, but the blue detuning is not conducive to the formation of the molecules. In addition, the differences of the adiabaticity and conversion efficiency among different reaction pathways are discussed.

Acta Physica Sinica•Jan 1, 2011•3 citations

Adiabatic fidelity for atom-molecule conversion in a nonlinear three-level Λ system

Shao-Ying Meng, Libin Fu, Jie Liu

By generalizing the definition of fidelity for the nonlinear system, we investigate the dynamics and adiabaticity of the population transfer for atom-molecule three-level $\ensuremath{\Lambda}$ system on a stimulated Raman adiabatic passage (STIRAP). We find that the adiabatic fidelity for the coherent population trapping state or dark state, as the function of the adiabatic parameter, approaches to unit in a power law. The power exponent, however, is much less than the prediction of the linear adiabatic theorem. We further discuss how to achieve higher adiabatic fidelity for the dark state through optimizing the external parameters of the STIRAP.

arXiv:0709.0359•Physical Review A•Nov 14, 2008•42 citations

Adiabatic evolution for the87Rb atom–molecule conversion system

Shao-Ying Meng, Libin Fu, Jie Liu

The adiabaticity of the stimulated Raman adiabatic passage (STIRAP) for the 87Rb atom–molecule conversion in a condensate system is investigated in terms of a newly defined adiabatic fidelity. The evolution of the dark state in the STIRAP is simulated numerically by considering the interparticle interactions and spontaneous emissions of the excited molecular state. We find that these terms will reduce the adiabatic fidelity; however, one can still achieve higher adiabatic fidelity through optimizing the external parameters of the STIRAP. Our discussions are helpful in obtaining higher conversion efficiency from an atomic Bose–Einstein condensate to its molecular counterpart in experiment.

Journal of Physics B Atomic Molecular and Optical Physics•Sep 8, 2009•1 citation
On the basis of the stimulated Raman adiabatic passage technology, we study the conversion of ultracold atoms into diatomic molecules by using a square-shaped pulse field. By the method of adiabatic fidelity, we analyze the dynamical evolution process of the coherent population trapping state for the atom-molecule conversion system. We introduce two adiabatic fidelities to describe the efficiency of ultracold atom-molecule conversion, i.e.:1) the final adiabatic fidelity, which gives the value of the adiabatic fidelity at the end of the evolution:the closer to 1 it is, the higher the conversion efficiency is; 2) the final maximum adiabatic fidelity, which denotes the maximum value that can be achieved at the end of evolution, indicating the highest conversion efficiency. With these two quantities, we discuss how to achieve higher adiabatic fidelity for the coherent population trapping state through optimizing the pulse-delay time and the pulse-laser intensity of the stimulated Raman adiabatic passage. In addition, we also discuss the effects of the width of pulses on the ultracold atom-molecule conversion efficiency and the feasibility of continuous light. It is shown that the final adiabatic fidelity of the coherent population trapping state demonstrates a large periodic oscillation with the pulse-laser intensity. By calculating and analyzing the final adiabatic fidelity and the final maximum adiabatic fidelity, we obtain the conditions for higher efficiency conversion, which gives the best choice of the pulse-laser intensity, the pulse-delay time, and the width of pulses. The results show that the scheme of square-shaped pulses we discussed has obvious advantages compared with that of Gaussian-shaped pulses, which can achieve high adiabatic fidelity and realize higher ultracold atom-molecule conversion efficiency via employing the pulse-laser field with low intensity. Further detailed comparison between the square-shaped pulses and the Gaussian-shaped pulses is also given. Particularly, we find that the final adiabatic fidelity shows a periodic oscillation with the pulse width, which means that the high efficiency atom-molecule conversion can be achieved by using a pulse field with small width. Moreover, we find that the high efficiency conversion can also be achieved by using special continuous light under certain conditions.
From the non-U（1） invariance of the atom-dimer conversion system, we generalized the definition of fidelity to this nonlinear system. By making use of the adiabatic fidelity, we investigated the dynamics and adiabaticity of the atom-dimer conversion system in a stimulated Raman adiabatic passage （STIRAP）. We found that the adiabatic fidelity for the coherent population trapping state or dark state, as the function of the adiabatic parameter, approaches to unity following a power law. The power exponent, however, is much smaller than that predicted by the linear adiabatic theorem. We further discuss how to achieve higher adiabatic fidelity for the dark state through optimizing the external parameters of STIRAP and hence to optimize the adiabaticity of the system and obtain high conversion efficiency.
The efficiency of converting two-species fermionic atoms into bosonic molecules is investigated in terms of mean-field Lagrangian density. We find that the stimulated Raman adiabatic passage technique aided by Feshbach resonance is more effective than the bare Feshbach resonance for 6Li^{6}\text{L}\text{i}6Li atoms rather than 40K^{40}\text{K}40K atoms. We also generally consider the symmetry and its relevant conservation law, which enables us to introduce a natural definition of adiabatic fidelity for a coherent population trapping state. The calculated values of the fidelity are presented and then we provide an explanation of why the conversion efficiencies for 40K^{40}\text{K}40K and 6Li^{6}\text{L}\text{i}6Li are distinctly different.
Due to the inevitability of nonlinear collisions between particles in ultracold atomic condensate experiments, it is of great significance to study the nonlinear effect for producing ultracold molecules from atomic condensates. In this work, we investigate theoretically the nonlinear effect induced by the two-body collision for producing ultracold Cs2 molecules from ultracold atoms by the stimulated Raman adiabatic passage in a tunneling four-level structure. Under the two-photon resonance condition and the coherent population trapping state, the conversion efficiency is influenced significantly by the nonlinear parameter. Meanwhile, the optimized parameter ranges of the resonance tunneling strength at the unstable excited molecular states, the effective Rabi frequencies of the two-laser fields, and the detuning of the pump field for different nonlinear parameters are suggested to obtain the high conversion efficiency of Cs2 molecules at the ground state. Finally, a maximum conversion efficiency of up to 88.56% can be realized in the optimized parameter ranges.
We investigate the effects of external field parameters, including the strength of Rabi pulse, its width, and single-photon detuning, on conversion from ultracold atoms to heteronuclear triatomic molecules by two-photon stimulated Raman adiabatic passage. It is found that the conversion efficiency of the system decreases first with the strength of the Stokes pulse increasing, then oscillates, and finally approaches a stable value, which is less than 1. But for the pump pulse, the efficiency first increases with the increase of the pulse intensity, and then approaches 1 quickly. The results show that the two pulses play different roles in the conversion. The pulse width can not only determine the final conversion efficiency, but also be used to reflect the time needed for stable conversion. The system has a higher efficiency of conversion for red detuning pump laser, but the blue detuning is not conducive to the formation of the molecules. In addition, the differences of the adiabaticity and conversion efficiency among different reaction pathways are discussed.
By generalizing the definition of fidelity for the nonlinear system, we investigate the dynamics and adiabaticity of the population transfer for atom-molecule three-level $\ensuremath{\Lambda}$ system on a stimulated Raman adiabatic passage (STIRAP). We find that the adiabatic fidelity for the coherent population trapping state or dark state, as the function of the adiabatic parameter, approaches to unit in a power law. The power exponent, however, is much less than the prediction of the linear adiabatic theorem. We further discuss how to achieve higher adiabatic fidelity for the dark state through optimizing the external parameters of the STIRAP.
The adiabaticity of the stimulated Raman adiabatic passage (STIRAP) for the 87Rb atom–molecule conversion in a condensate system is investigated in terms of a newly defined adiabatic fidelity. The evolution of the dark state in the STIRAP is simulated numerically by considering the interparticle interactions and spontaneous emissions of the excited molecular state. We find that these terms will reduce the adiabatic fidelity; however, one can still achieve higher adiabatic fidelity through optimizing the external parameters of the STIRAP. Our discussions are helpful in obtaining higher conversion efficiency from an atomic Bose–Einstein condensate to its molecular counterpart in experiment.