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:2403.14288

Formation of ultracold deeply-bound molecules via multi-state chainwise coincident pulses technique

Jiahui Zhang

Published Mar 21, 2024• 0 citations
arXivHTMLPDF

Abstract

In this paper, a theoretical method for the efficient creation and detection of deeply bound molecules in three-state $Λ$-type and five-state M-type molecular systems is proposed. The method is based on the three-state coincident pulses technique and the generalized five-state coincident pulses technique. For the three-state system, the technique can efficiently transfer the populations from the Feshbach state to the deeply-bound state via a train of $N$ pairs of resonant and coincident pump and Stokes pulses, with negligible transient populations of excited states. For the five-state system, it is found that this M-type system can be generalized into a $Λ$-type structure with the simplest resonant coupling under the assumption of large one-photon detuning together with a requirement of the relation among the four incident pulses. Thereafter, this generalized model permits us to employ the reduced three-state propagator to design four coincident pulses to achieve the desired population transfer. For the numerical study, $^{87}$Rb$_2$ is considered and, it is shown that the weakly-bound Feshbach molecules can be efficiently transferred to their deeply-bound states without strong laser pulses, and the populations of all intermediate states can be well suppressed.

DOI
10.48550/arxiv.2403.14288

Related papers

Highly efficient creation and detection of ultracold deeply bound molecules via chainwise stimulated Raman shortcut-to-adiabatic passage

Jiahui Zhang, Li Deng, Yueping Niu +1 more

Chainwise stimulated Raman adiabatic passage (C-STIRAP) in a M-type molecular system is a good alternative in creating ultracold deeply bound molecules when the typical STIRAP in a $\mathrm{\ensuremath{\Lambda}}$-type system does not work due to weak Frank-Condon factors between states. However, its creation efficiency under smooth evolution is generally low. During the process, the population in the intermediate states may decay out quickly and the strong laser pulses may induce multiphoton processes. In this paper, we find that the shortcut to adiabaticity (STA) fits very well in improving the performance of the C-STIRAP. Currently, related discussions on the so-called chainwise stimulated Raman shortcut-to-adiabatic passage (C-STIRSAP) are rare. Here, we investigate this topic under adiabatic elimination. Given a relation among the four incident pulses, it is quite interesting that the M-type system can be generalized into an effective $\mathrm{\ensuremath{\Lambda}}$-type structure with the simplest resonant coupling. Consequently, all possible methods of STA for the three-state system can be borrowed. We take the counterdiabatic driving and ``chosen path'' methods as instances to demonstrate our treatment of the molecular system. Although the chosen path method does not work well in a real three-state system if there is strong decay in the excited state, our C-STIRSAP protocol under both methods can create ultracold deeply bound molecules with high efficiency in the M-type system. The evolution time is shortened without strong laser pulses and the robustness of STA is well preserved. Finally, the detection of ultracold deeply bound molecules is discussed.

arXiv:2310.11071•Physical Review A•Feb 9, 2024•6 citations

Quantum state engineering in a five-state chainwise system by generalized coincident pulse technique

Jiahui Zhang

In this paper, an exact analytical solution is presented for achieving coherent population transfer and creating arbitrary coherent superposition states in a five-state chainwise system by a train of coincident pulses. We show that the solution of a five-state chainwise system can be reduced to an equivalent three-state Λ-type one with the simplest resonant coupling under the assumption of adiabatic elimination together with a requirement of the relation among the four coincident pulses. In this method, the four coincident pulses at each step all have the same time dependence, but with specific magnitudes. The results show that, by using a train of appropriately coincident pulses, this technique not only enables complete population transfer, but also creates any desired coherent superposition between the initial and final states, while the population in all intermediate states is effectively suppressed. Furthermore, this technique can also exhibit a one-way population transfer behavior. The results are of potential interest in applications where high-fidelity multi-state quantum control is essential, e.g., quantum information, atom optics, formation of ultracold molecules, cavity QED, nuclear coherent population transfer, and light transfer in waveguide arrays.

arXiv:2311.15686•The Journal of Chemical Physics•Aug 15, 2024•1 citation

Highly efficient creation and detection of deeply bound molecules via invariant-based inverse engineering with feasible modified drivings

Jiahui Zhang

Stimulated Raman Adiabatic Passage (STIRAP) and its variants, such as M-type chainwise-STIRAP, allow for efficiently transferring the populations in a multilevel system and have widely been used to prepare molecules in their rovibrational ground state. However, their transfer efficiencies are generally imperfect. The main obstacle is the presence of losses and the requirement to make the dynamics adiabatic. To this end, in the present paper, a new theoretical method is proposed for the efficient and robust creation and detection of deeply bound molecules in three-level Λ-type and five-level M-type systems via "Invariant-based shortcut-to-adiabaticity." In the regime of large detunings, we first reduce the dynamics of three- and five-level molecular systems to those of effective two- and three-level counterparts. By doing so, the major molecular losses from the excited states can be well suppressed. Consequently, the effective two-level counterpart can be directly compatible with two different "Invariant-based Inverse Engineering" protocols; the results show that both protocols give a comparable performance and have a good experimental feasibility. For the effective three-level counterpart, by considering a relation among the four incident pulses, we show that this model can be further generalized to an effective Λ-type one with the simplest resonant coupling. This generalized model permits us to borrow the "Invariant-based Inverse Engineering" protocol from a standard three-level Λ-type system to a five-level M-type system. Numerical calculations show that the weakly bound molecules can be efficiently transferred to their deeply bound states without strong laser pulses, and the stability against parameter variations is well preserved. Finally, the detection of ultracold deeply bound molecules is discussed.

arXiv:2310.14499•The Journal of Chemical Physics•Jan 8, 2024•2 citations

Formation of deeply bound molecules via chainwise adiabatic passage

Elena Kuznetsova, Philippe Pellegrini, Robin Côté +2 more

We suggest and analyze a technique for efficient and robust creation of dense ultracold molecular ensembles in their ground rovibrational state. In our approach a molecule is brought to the ground state through a series of intermediate vibrational states via a multistate chainwise stimulated Raman adiabatic passage technique. We study the influence of the intermediate states decay on the transfer process and suggest an approach that minimizes the population of these states, resulting in a maximal transfer efficiency. As an example, we analyze the formation of $^{87}\mathrm{Rb}_{2}$ starting from an initial Feshbach molecular state and taking into account major decay mechanisms due to inelastic atom-molecule and molecule-molecule collisions. Numerical analysis suggests a transfer efficiency $>90%$, even in the presence of strong collisional relaxation as are present in a high density atomic gas.

arXiv:0806.0821•Physical Review A•Aug 5, 2008•28 citations

Effective creation of ultracold deeply-bound molecules via non-Hermitian stimulated Raman shortcut-to-adiabatic passage

Jiahui Zhang, Nida Naim, Li Fei Deng +2 more

In this paper, we carry out the non-Hermitian stimulated Raman shortcut-to-adiabatic passage (NH-STIRSAP) to create ultracold deeply-bound molecules. The open three-level molecular system is supposed to have irreversible decays out of all levels. Under the assumption of large single-photon detuning and/or strong loss rate of the excited level, the NH three-level system can be theoretically reduced to an effective two-level system. By continuously using the counter-diabatic driving of the shortcut-to-adiabaticity, an auxiliary field is produced to couple the Feshbach level with the ground level. In the numerical calculations, we firstly consider the case of decaying only from the excited level, which is the main loss of the system. Under the NH-STIRSAP, the calculations reveal that complete population transfer from the Feshbach to the ground level can occur even if the adiabatic condition is not fulfilled. Therefore, the creation efficiency of ultracold deeply-bound molecules is greatly improved. The results hold equally for counter-intuitive and intuitive time sequence of the Stokes and pump pulse. If the decays from the Feshbach and ground level are also included, the NH-STIRSAP can still restore most of that efficiency, which performs much better than typical stimulated Raman adiabatic passage. Finally, we point out that the robustness and fast transfer speed of the NH-STIRSAP facilitate the creation and detection of ultracold deeply-bound molecules.

Results in Physics•Apr 1, 2023•3 citations

The formation of ultracold rubidium molecules using ultrafast photoassociation

David J. McCabe, David J. McCabe

The establishment of robust laser-cooling techniques for the formation of ultracold atoms has provided a test-bed for low-temperature science, with scattering events changing character from incoherent thermal interactions to coherent quantum mechanical events. A natural extension is the pursuit of ultracold molecules in prescribed low-energy internal states. Atomic cooling techniques, however, do not generalize to the molecular regime due to the complex energy-level structure afforded by its extra degrees of motion. An indirect approach to ultracold molecule formation - photoassociation using ultrafast laser pulses - is the focus of this thesis. A broadband field associates atom pairs into a localized molecular wavepacket that evolves within the attractive excited-state potential. A suitably timed dump pulse may thus be applied to stabilize population into deeply bound ground vibrational states. This strategy may be generalized to any species whose spectroscopy matches the pulse spectrum, and offers a coherent population transfer scheme that does not require precise knowledge of the system. This thesis presents experiments using high-energy photoassociation pulses applied to ultracold rubidium atoms. The pulses quench the background ground-state molecular population but form bound dimers within the excited state. A pump-probe experiment was designed to chart the excited-state dynamics; however, the oscillations predicted by theoretical calculations were not evident in the molecular signal. The nature of the dynamics is expected to be strongly dependent on the initial state of the atom pairs addressed by the ultrafast pulse: a bound molecular population provides an additional candidate to free atoms. A spectroscopic measurement characterizes these bound molecules and identifies their formation mechanism. A subsequent experiment provides evidence that the predominant contributor to the pump-probe signal is the unbound initial population. The consequences with regard to both the observation of excited-state dynamics and the subsequent application of a dump pulse are discussed.

•Jan 1, 2010•1 citation
In this paper, a theoretical method for the efficient creation and detection of deeply bound molecules in three-state ΛΛΛ-type and five-state M-type molecular systems is proposed. The method is based on the three-state coincident pulses technique and the generalized five-state coincident pulses technique. For the three-state system, the technique can efficiently transfer the populations from the Feshbach state to the deeply-bound state via a train of NNN pairs of resonant and coincident pump and Stokes pulses, with negligible transient populations of excited states. For the five-state system, it is found that this M-type system can be generalized into a ΛΛΛ-type structure with the simplest resonant coupling under the assumption of large one-photon detuning together with a requirement of the relation among the four incident pulses. Thereafter, this generalized model permits us to employ the reduced three-state propagator to design four coincident pulses to achieve the desired population transfer. For the numerical study, 87^{87}87Rb2_22​ is considered and, it is shown that the weakly-bound Feshbach molecules can be efficiently transferred to their deeply-bound states without strong laser pulses, and the populations of all intermediate states can be well suppressed.
Chainwise stimulated Raman adiabatic passage (C-STIRAP) in a M-type molecular system is a good alternative in creating ultracold deeply bound molecules when the typical STIRAP in a $\mathrm{\ensuremath{\Lambda}}$-type system does not work due to weak Frank-Condon factors between states. However, its creation efficiency under smooth evolution is generally low. During the process, the population in the intermediate states may decay out quickly and the strong laser pulses may induce multiphoton processes. In this paper, we find that the shortcut to adiabaticity (STA) fits very well in improving the performance of the C-STIRAP. Currently, related discussions on the so-called chainwise stimulated Raman shortcut-to-adiabatic passage (C-STIRSAP) are rare. Here, we investigate this topic under adiabatic elimination. Given a relation among the four incident pulses, it is quite interesting that the M-type system can be generalized into an effective $\mathrm{\ensuremath{\Lambda}}$-type structure with the simplest resonant coupling. Consequently, all possible methods of STA for the three-state system can be borrowed. We take the counterdiabatic driving and ``chosen path'' methods as instances to demonstrate our treatment of the molecular system. Although the chosen path method does not work well in a real three-state system if there is strong decay in the excited state, our C-STIRSAP protocol under both methods can create ultracold deeply bound molecules with high efficiency in the M-type system. The evolution time is shortened without strong laser pulses and the robustness of STA is well preserved. Finally, the detection of ultracold deeply bound molecules is discussed.
In this paper, an exact analytical solution is presented for achieving coherent population transfer and creating arbitrary coherent superposition states in a five-state chainwise system by a train of coincident pulses. We show that the solution of a five-state chainwise system can be reduced to an equivalent three-state Λ-type one with the simplest resonant coupling under the assumption of adiabatic elimination together with a requirement of the relation among the four coincident pulses. In this method, the four coincident pulses at each step all have the same time dependence, but with specific magnitudes. The results show that, by using a train of appropriately coincident pulses, this technique not only enables complete population transfer, but also creates any desired coherent superposition between the initial and final states, while the population in all intermediate states is effectively suppressed. Furthermore, this technique can also exhibit a one-way population transfer behavior. The results are of potential interest in applications where high-fidelity multi-state quantum control is essential, e.g., quantum information, atom optics, formation of ultracold molecules, cavity QED, nuclear coherent population transfer, and light transfer in waveguide arrays.
Stimulated Raman Adiabatic Passage (STIRAP) and its variants, such as M-type chainwise-STIRAP, allow for efficiently transferring the populations in a multilevel system and have widely been used to prepare molecules in their rovibrational ground state. However, their transfer efficiencies are generally imperfect. The main obstacle is the presence of losses and the requirement to make the dynamics adiabatic. To this end, in the present paper, a new theoretical method is proposed for the efficient and robust creation and detection of deeply bound molecules in three-level Λ-type and five-level M-type systems via "Invariant-based shortcut-to-adiabaticity." In the regime of large detunings, we first reduce the dynamics of three- and five-level molecular systems to those of effective two- and three-level counterparts. By doing so, the major molecular losses from the excited states can be well suppressed. Consequently, the effective two-level counterpart can be directly compatible with two different "Invariant-based Inverse Engineering" protocols; the results show that both protocols give a comparable performance and have a good experimental feasibility. For the effective three-level counterpart, by considering a relation among the four incident pulses, we show that this model can be further generalized to an effective Λ-type one with the simplest resonant coupling. This generalized model permits us to borrow the "Invariant-based Inverse Engineering" protocol from a standard three-level Λ-type system to a five-level M-type system. Numerical calculations show that the weakly bound molecules can be efficiently transferred to their deeply bound states without strong laser pulses, and the stability against parameter variations is well preserved. Finally, the detection of ultracold deeply bound molecules is discussed.
We suggest and analyze a technique for efficient and robust creation of dense ultracold molecular ensembles in their ground rovibrational state. In our approach a molecule is brought to the ground state through a series of intermediate vibrational states via a multistate chainwise stimulated Raman adiabatic passage technique. We study the influence of the intermediate states decay on the transfer process and suggest an approach that minimizes the population of these states, resulting in a maximal transfer efficiency. As an example, we analyze the formation of 87Rb2^{87}\mathrm{Rb}_{2}87Rb2​ starting from an initial Feshbach molecular state and taking into account major decay mechanisms due to inelastic atom-molecule and molecule-molecule collisions. Numerical analysis suggests a transfer efficiency >90>90%>90, even in the presence of strong collisional relaxation as are present in a high density atomic gas.
In this paper, we carry out the non-Hermitian stimulated Raman shortcut-to-adiabatic passage (NH-STIRSAP) to create ultracold deeply-bound molecules. The open three-level molecular system is supposed to have irreversible decays out of all levels. Under the assumption of large single-photon detuning and/or strong loss rate of the excited level, the NH three-level system can be theoretically reduced to an effective two-level system. By continuously using the counter-diabatic driving of the shortcut-to-adiabaticity, an auxiliary field is produced to couple the Feshbach level with the ground level. In the numerical calculations, we firstly consider the case of decaying only from the excited level, which is the main loss of the system. Under the NH-STIRSAP, the calculations reveal that complete population transfer from the Feshbach to the ground level can occur even if the adiabatic condition is not fulfilled. Therefore, the creation efficiency of ultracold deeply-bound molecules is greatly improved. The results hold equally for counter-intuitive and intuitive time sequence of the Stokes and pump pulse. If the decays from the Feshbach and ground level are also included, the NH-STIRSAP can still restore most of that efficiency, which performs much better than typical stimulated Raman adiabatic passage. Finally, we point out that the robustness and fast transfer speed of the NH-STIRSAP facilitate the creation and detection of ultracold deeply-bound molecules.
The establishment of robust laser-cooling techniques for the formation of ultracold atoms has provided a test-bed for low-temperature science, with scattering events changing character from incoherent thermal interactions to coherent quantum mechanical events. A natural extension is the pursuit of ultracold molecules in prescribed low-energy internal states. Atomic cooling techniques, however, do not generalize to the molecular regime due to the complex energy-level structure afforded by its extra degrees of motion. An indirect approach to ultracold molecule formation - photoassociation using ultrafast laser pulses - is the focus of this thesis. A broadband field associates atom pairs into a localized molecular wavepacket that evolves within the attractive excited-state potential. A suitably timed dump pulse may thus be applied to stabilize population into deeply bound ground vibrational states. This strategy may be generalized to any species whose spectroscopy matches the pulse spectrum, and offers a coherent population transfer scheme that does not require precise knowledge of the system. This thesis presents experiments using high-energy photoassociation pulses applied to ultracold rubidium atoms. The pulses quench the background ground-state molecular population but form bound dimers within the excited state. A pump-probe experiment was designed to chart the excited-state dynamics; however, the oscillations predicted by theoretical calculations were not evident in the molecular signal. The nature of the dynamics is expected to be strongly dependent on the initial state of the atom pairs addressed by the ultrafast pulse: a bound molecular population provides an additional candidate to free atoms. A spectroscopic measurement characterizes these bound molecules and identifies their formation mechanism. A subsequent experiment provides evidence that the predominant contributor to the pump-probe signal is the unbound initial population. The consequences with regard to both the observation of excited-state dynamics and the subsequent application of a dump pulse are discussed.