Sound speed of a Bose-Einstein condensate in an optical lattice

Abstract

The speed of sound of a Bose-Einstein condensate in an optical lattice is studied both analytically and numerically in all three dimensions. Our investigation shows that the sound speed depends strongly on the strength of the lattice. In the one-dimensional case, the speed of sound falls monotonically with increasing lattice strength. The dependence on lattice strength becomes much richer in two and three dimensions. In the two-dimensional case, when the interaction is weak, the sound speed first increases then decreases as the lattice strength increases. For the three dimensional lattice, the sound speed can even oscillate with the lattice strength. These rich behaviors can be understood in terms of compressibility and effective mass. Our analytical results at the limit of weak lattices also offer an interesting perspective to the understanding: they show the lattice component perpendicular to the sound propagation increases the sound speed while the lattice components parallel to the propagation decreases the sound speed. The various dependence of the sound speed on the lattice strength is the result of this competition.

15pages 6 figures

References in corpus (5)

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Cited by in corpus (22)

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• Bogoliubov Excitations of Disordered Bose-Einstein Condensates
• Bragg spectroscopy of a superfluid Bose-Hubbard gas
• Stability Spectroscopy of Rotons in a Dipolar Bose Gas
• Probing the Flat Band of Optically-Trapped Spin-Orbital Coupled Bose Gases Using Bragg Spectroscopy
• Spinor polariton condensates under nonresonant pumping: Steady states and elementary excitations
• Beliaev Damping in Spin-$\frac{1}{2}$ Interacting Bosons with Spin-Orbit Coupling
• Geometric Stability Spectra of Dipolar Bose Gases in Tunable Optical Lattices
• High- and low-frequency phonon modes in dipolar quantum gases trapped in deep lattices
• Collective excitations of a trapped Bose-Einstein condensate in the presence of weak disorder and a two-dimensional optical lattice
• Superfluidity breakdown of periodic matter waves in quasi one-dimensional annular traps via resonant scattering with moving defects
• Optically trapped quasi-two-dimensional Bose gases in random environment: quantum fluctuations and superfluid density
• Non-equilibrium quantum phase transition in a spinor quantum gas in a lattice coupled to a membrane
• Matter sound waves in two-component Bose-Einstein condensates
• Scattering tightly bound dimers off a scattering potential
• Exact nonlinear Bloch-state solutions for Bose-Einstein condensates in a periodic array of quantum wells
• Interaction between an impurity and nonlinear excitations in a polariton condensate
• Probing Sound Speed of an Optically-Trapped Bose Gas with Periodically Modulated Interactions by Bragg Spectroscopy
• Unusual behavior of sound velocity of a Bose gas in an optical superlattice at quasi-one-dimension
• Speed of sound of a Bose--Einstein condensate with dipole--dipole interactions
• Dispersion Managed Elliptical Atomtronics for Interferometry
• Density wave propagation in a two-dimensional random dimer potential: from a single to a bipartite square lattice