Ground-state phase and superfluidity of tunable spin-orbit-coupled Bose-Einstein condensates

Area of Science:

• Quantum Physics
• Atomic, Molecular, and Optical Physics
• Condensed Matter Physics

Background:

• Spin-orbit-coupled Bose-Einstein condensates (BECs) exhibit complex ground-state phases and superfluid properties.
• Controlling these properties is crucial for fundamental understanding and potential applications.

Purpose of the Study:

• To theoretically investigate the ground-state phases and superfluidity of tunable spin-orbit-coupled BECs.
• To explore the effects of periodic driving via Raman coupling on BEC properties.
• To determine if periodic driving can be used to manipulate phase transitions and superfluidity.

Main Methods:

• Development of an effective time-independent Floquet Hamiltonian using a high-frequency approximation.
• Analytical derivation of critical Raman coupling and physical quantities for different phases.
• Investigation of single-particle dispersion, spin-orbit coupling, and nonlinear interactions.

Main Results:

• Periodic driving effectively modulates single-particle dispersion, spin-orbit coupling, and nonlinear interactions.
• Ground-state phase boundaries are controllable, leading to three distinct phase transitions (stripe, plane-wave, zero momentum).
• Periodic driving enhances stripe density contrast and tunes dynamical instability and sound velocity in superfluid states.

Conclusions:

• Periodic driving of Raman coupling offers a powerful method to precisely control ground-state phases and superfluidity in spin-orbit-coupled BECs.
• The study demonstrates the tunability of phase transitions and dynamical instability through external driving.
• Findings provide a new avenue for manipulating quantum many-body systems.