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:2404.14791 · Physical Review A

Phase separation and metastability in a mixture of spin-1 and spin-2 Bose-Einstein condensates

Uyen Ngoc Le, Hieu Binh Le, Hiroki Saito

Published Sep 25, 2024• 1 citation
arXivHTMLPDF

Abstract

We investigate the ground state and dynamics of a mixture of spin-1 and spin-2 Bose-Einstein condensates of $^{87}\mathrm{Rb}$ atoms. For the experimentally measured interaction coefficients, the ground state exhibits phase separation between the spin-1 ferromagnetic state and the spin-2 nematic state. At the interface between them, a partially polarized spin state emerges. The uniformly mixed state of the spin-1 polar state and spin-2 biaxial nematic state is metastable, and the phase separation via nucleation can be triggered by a local disturbance.

DOI
10.1103/physreva.110.033328

Related papers

Mixed bubbles in a binary mixture of spin-1 Bose-Einstein condensates

Uyen Ngoc Le, Ha Phuong Uyen Mai, Hieu Binh Le +1 more

In mean-field theory, the ground state of a two-component Bose-Einstein condensate (BEC) in a uniform system is either uniformly mixed or totally separated. Beyond-mean-field effects introduce an additional phase, the mixed-bubble state, in which the two components remain mixed within one of the separated domains. Here we show that a mixed-bubble state can emerge in a binary mixture of spin-1 ${}^{7}{\rm{Li}}$ and ${}^{23}{\rm{Na}}$ BECs even within the mean-field framework. We further demonstrate the existence of a metastable uniformly-mixed state, which undergoes a transition to the mixed-bubble state triggered by a local perturbation.

arXiv:2609.39231•Sep 30, 2026•0 citations

Spinor dynamics in a mixture of spin-1 and spin-2 Bose-Einstein condensates

Yujiro Eto, Hitoshi Shibayama, Hiroki Saito +1 more

The spinor dynamics of Bose-Einstein condensates of $^{87}\mathrm{Rb}$ atoms with hyperfine spins of 1 and 2 are investigated. A mixture of spinor condensates is generated in the transversely polarized spin-1 and the longitudinally polarized spin-2 states using simultaneous Ramsey interferometry. In the subsequent dynamics, temporal modulation of spin-1 magnetization is observed in the spinor mixture due to the spin-dependent interaction with the spin-2 component. By comparison with numerical simulations based on the Gross-Pitaevskii equation, we find that the observed nonferromagnetic dynamics reflect the ground-state properties of the spinor mixture.

arXiv:1707.02660•Physical Review A•Feb 13, 2018•17 citations

Metastable spin-phase diagrams in antiferromagnetic Bose-Einstein condensates

Eduardo Serrano-Ensástiga, Francisco Mireles

Spinor Bose-Einstein condensates under external magnetic fields exhibit well-characterized spin domains of its ground state due to spin-dependent interactions. At low temperatures, collision-induced spin-mixing instabilities may promote the condensate to dwell into metastable states occurring near the phase boundaries. In this paper, we study theoretically the metastable spin-phase diagram of a spin-1 antiferromagnetic Bose-Einstein condensate at zero and finite temperatures. The approach makes use of Hartree-Fock theory and exploits the symmetry of the Hamiltonian and of the order parameters yielding a closed system of transcendental equations for the free energy, fully avoiding the use of self-consistency methods. Our results are consistent with recent experiments and allow us to explain qualitatively the different types of observed quench dynamics. In addition, we found that similar phenomena should occur in antiferromagnetic spinor condensates with a sudden change in the temperature. It is shown also that the increase in temperature induces a traceable shift of the ferromagnetic-polar transition boundary, behavior previously not noted by self-consistent mean-field calculations.

arXiv:2109.01986•Physical Review A•Dec 13, 2021•4 citations

Ground-state phases of a mixture of spin-1 and spin-2 Bose-Einstein condensates

Naoki Irikura, Yujiro Eto, Takuya Hirano +1 more

We investigate the ground-state phases of a mixture of spin-1 and spin-2 Bose-Einstein condensates at zero magnetic field. In addition to the intraspin interactions, two spin-dependent interaction coefficients are introduced to describe the interspin interaction. We systematically explore the wide parameter space, and obtain phase diagrams containing a rich variety of phases. For example, there exists a phase in which the spin-1 and spin-2 vectors are tilted relative to each other breaking the axial symmetry.

arXiv:1712.05111•Physical Review A•Feb 13, 2018•20 citations

Bose-Einstein condensates in a spin-twisted harmonic trap

Huaxin He, Fengtao Pang, Xianchao Zhang +2 more

We investigate the ground-state phases and spin-scissors dynamics of binary Bose-Einstein condensates confined in a twisted two-dimensional harmonic trap. The ground state hosts three distinct phases-phase-separated, polarized, and phase-mixed-determined by the Rabi coupling, interaction ratio G (between inter-component and intra-component interactions), and spin-twisting which induces edge-localized polarization through position-dependent detuning. In the phase-mixed regime, the ground state is characterized by a finite spin-scissors susceptibility and can be accurately described using local density approximation. In the dynamics, the system exhibits stable periodic beating in the phase-mixed state for G<1. For G>1, its evolution progresses from beat damping (phase-separated state) to polarized relaxation (polarized state), finally reaching stable periodic beating (phase-mixed state) after a finite waiting time. The dependence of the waiting time contrasts sharply with the monotonic behavior of one-dimensional spin-dipole dynamics, revealing qualitatively distinct mechanisms governed by geometry and interactions. In summary, these results establish a unified link between ground-state properties and nonequilibrium responses in twisted spinor condensates, offering a versatile platform for exploring spin-related quantum many-body phenomena.

arXiv:2509.11769•Physical Review A•Dec 23, 2025•0 citations

Excited spin states and phase separation in spinor Bose-Einstein condensates

Michał Matuszewski, Tristram J. Alexander, Yuri S. Kivshar

We analyze the structure of spin-one Bose-Einstein condensates in the presence of a homogeneous magnetic field. We classify the homogeneous stationary states and study their existence, bifurcations, and energy spectra. We reveal that phase separation can occur in the ground state of antiferromagnetic (polar) condensates while the spin components of the ferromagnetic condensates are always miscible and no phase separation occurs. Our theoretical model, confirmed by numerical simulations, explains that this phenomenon takes place when the energy of the lowest homogeneous state is a concave function of the magnetization. In particular, we predict that phase separation can be observed in a $^{23}\text{N}\text{a}$ condensate confined in a highly elongated harmonic trap. Finally, we discuss the phenomena of dynamical instability and spin domain formation.

arXiv:0904.0086•Physical Review A•Aug 5, 2009•42 citations
We investigate the ground state and dynamics of a mixture of spin-1 and spin-2 Bose-Einstein condensates of 87Rb^{87}\mathrm{Rb}87Rb atoms. For the experimentally measured interaction coefficients, the ground state exhibits phase separation between the spin-1 ferromagnetic state and the spin-2 nematic state. At the interface between them, a partially polarized spin state emerges. The uniformly mixed state of the spin-1 polar state and spin-2 biaxial nematic state is metastable, and the phase separation via nucleation can be triggered by a local disturbance.
In mean-field theory, the ground state of a two-component Bose-Einstein condensate (BEC) in a uniform system is either uniformly mixed or totally separated. Beyond-mean-field effects introduce an additional phase, the mixed-bubble state, in which the two components remain mixed within one of the separated domains. Here we show that a mixed-bubble state can emerge in a binary mixture of spin-1 7Li{}^{7}{\rm{Li}}7Li and 23Na{}^{23}{\rm{Na}}23Na BECs even within the mean-field framework. We further demonstrate the existence of a metastable uniformly-mixed state, which undergoes a transition to the mixed-bubble state triggered by a local perturbation.
The spinor dynamics of Bose-Einstein condensates of 87Rb^{87}\mathrm{Rb}87Rb atoms with hyperfine spins of 1 and 2 are investigated. A mixture of spinor condensates is generated in the transversely polarized spin-1 and the longitudinally polarized spin-2 states using simultaneous Ramsey interferometry. In the subsequent dynamics, temporal modulation of spin-1 magnetization is observed in the spinor mixture due to the spin-dependent interaction with the spin-2 component. By comparison with numerical simulations based on the Gross-Pitaevskii equation, we find that the observed nonferromagnetic dynamics reflect the ground-state properties of the spinor mixture.
Spinor Bose-Einstein condensates under external magnetic fields exhibit well-characterized spin domains of its ground state due to spin-dependent interactions. At low temperatures, collision-induced spin-mixing instabilities may promote the condensate to dwell into metastable states occurring near the phase boundaries. In this paper, we study theoretically the metastable spin-phase diagram of a spin-1 antiferromagnetic Bose-Einstein condensate at zero and finite temperatures. The approach makes use of Hartree-Fock theory and exploits the symmetry of the Hamiltonian and of the order parameters yielding a closed system of transcendental equations for the free energy, fully avoiding the use of self-consistency methods. Our results are consistent with recent experiments and allow us to explain qualitatively the different types of observed quench dynamics. In addition, we found that similar phenomena should occur in antiferromagnetic spinor condensates with a sudden change in the temperature. It is shown also that the increase in temperature induces a traceable shift of the ferromagnetic-polar transition boundary, behavior previously not noted by self-consistent mean-field calculations.
We investigate the ground-state phases of a mixture of spin-1 and spin-2 Bose-Einstein condensates at zero magnetic field. In addition to the intraspin interactions, two spin-dependent interaction coefficients are introduced to describe the interspin interaction. We systematically explore the wide parameter space, and obtain phase diagrams containing a rich variety of phases. For example, there exists a phase in which the spin-1 and spin-2 vectors are tilted relative to each other breaking the axial symmetry.
We investigate the ground-state phases and spin-scissors dynamics of binary Bose-Einstein condensates confined in a twisted two-dimensional harmonic trap. The ground state hosts three distinct phases-phase-separated, polarized, and phase-mixed-determined by the Rabi coupling, interaction ratio G (between inter-component and intra-component interactions), and spin-twisting which induces edge-localized polarization through position-dependent detuning. In the phase-mixed regime, the ground state is characterized by a finite spin-scissors susceptibility and can be accurately described using local density approximation. In the dynamics, the system exhibits stable periodic beating in the phase-mixed state for G<1. For G>1, its evolution progresses from beat damping (phase-separated state) to polarized relaxation (polarized state), finally reaching stable periodic beating (phase-mixed state) after a finite waiting time. The dependence of the waiting time contrasts sharply with the monotonic behavior of one-dimensional spin-dipole dynamics, revealing qualitatively distinct mechanisms governed by geometry and interactions. In summary, these results establish a unified link between ground-state properties and nonequilibrium responses in twisted spinor condensates, offering a versatile platform for exploring spin-related quantum many-body phenomena.
We analyze the structure of spin-one Bose-Einstein condensates in the presence of a homogeneous magnetic field. We classify the homogeneous stationary states and study their existence, bifurcations, and energy spectra. We reveal that phase separation can occur in the ground state of antiferromagnetic (polar) condensates while the spin components of the ferromagnetic condensates are always miscible and no phase separation occurs. Our theoretical model, confirmed by numerical simulations, explains that this phenomenon takes place when the energy of the lowest homogeneous state is a concave function of the magnetization. In particular, we predict that phase separation can be observed in a 23Na^{23}\text{N}\text{a}23Na condensate confined in a highly elongated harmonic trap. Finally, we discuss the phenomena of dynamical instability and spin domain formation.