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Ground states of a Bose-Einstein Condensate in a one-dimensional laser-assisted optical lattice

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ABSTRACT

We study the ground-state behavior of a Bose-Einstein Condensate (BEC) in a Raman-laser-assisted one-dimensional (1D) optical lattice potential forming a multilayer system. We find that, such system can be described by an effective model with spin-orbit coupling (SOC) of pseudospin (N-1)/2, where N is the number of layers. Due to the intricate interplay between atomic interactions, SOC and laser-assisted tunnelings, the ground-state phase diagrams generally consist of three phases–a stripe, a plane wave and a normal phase with zero-momentum, touching at a quantum tricritical point. More important, even though the single-particle states only minimize at zero-momentum for odd N, the many-body ground states may still develop finite momenta. The underlying mechanisms are elucidated. Our results provide an alternative way to realize an effective spin-orbit coupling of Bose gas with the Raman-laser-assisted optical lattice, and would also be beneficial to the studies on SOC effects in spinor Bose systems with large spin.

No MeSH data available.


Phase diagram in g2D − J plane for N = 2, consist of three phases: Stripe, Plane Wave and Normal phases (see the context for detail), touching at a tricritical point.The color bar denotes the magnitude of ground state momentum. The green solid lines label the parameters we used in Fig. (4b).
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f3: Phase diagram in g2D − J plane for N = 2, consist of three phases: Stripe, Plane Wave and Normal phases (see the context for detail), touching at a tricritical point.The color bar denotes the magnitude of ground state momentum. The green solid lines label the parameters we used in Fig. (4b).

Mentions: To be more specific and without loss of generality, we choose the simplest N = 2 for illustrations. In Fig. (3), we give the ground-state phase diagram in the g2D − J plane for N = 2 by numerically minimizing the energy EG. Generally, due to the interplay between atomic tunneling and atom-atom interactions, above three phases may compete with each other and survive in three distinct regimes (labeled by colors), touching at a tricritical point.


Ground states of a Bose-Einstein Condensate in a one-dimensional laser-assisted optical lattice
Phase diagram in g2D − J plane for N = 2, consist of three phases: Stripe, Plane Wave and Normal phases (see the context for detail), touching at a tricritical point.The color bar denotes the magnitude of ground state momentum. The green solid lines label the parameters we used in Fig. (4b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121596&req=5

f3: Phase diagram in g2D − J plane for N = 2, consist of three phases: Stripe, Plane Wave and Normal phases (see the context for detail), touching at a tricritical point.The color bar denotes the magnitude of ground state momentum. The green solid lines label the parameters we used in Fig. (4b).
Mentions: To be more specific and without loss of generality, we choose the simplest N = 2 for illustrations. In Fig. (3), we give the ground-state phase diagram in the g2D − J plane for N = 2 by numerically minimizing the energy EG. Generally, due to the interplay between atomic tunneling and atom-atom interactions, above three phases may compete with each other and survive in three distinct regimes (labeled by colors), touching at a tricritical point.

View Article: PubMed Central - PubMed

ABSTRACT

We study the ground-state behavior of a Bose-Einstein Condensate (BEC) in a Raman-laser-assisted one-dimensional (1D) optical lattice potential forming a multilayer system. We find that, such system can be described by an effective model with spin-orbit coupling (SOC) of pseudospin (N-1)/2, where N is the number of layers. Due to the intricate interplay between atomic interactions, SOC and laser-assisted tunnelings, the ground-state phase diagrams generally consist of three phases–a stripe, a plane wave and a normal phase with zero-momentum, touching at a quantum tricritical point. More important, even though the single-particle states only minimize at zero-momentum for odd N, the many-body ground states may still develop finite momenta. The underlying mechanisms are elucidated. Our results provide an alternative way to realize an effective spin-orbit coupling of Bose gas with the Raman-laser-assisted optical lattice, and would also be beneficial to the studies on SOC effects in spinor Bose systems with large spin.

No MeSH data available.