Bose-Einstein condensation in low dimensional layered structures

Kwangsik T. Nho, D. P. Landau

P. Surendran

This thesis reports the realization of Bose-Einstein condensation (BEC) of 87Rb F=1 atoms in multiple sites of a one-dimensional 10 μm-periods magnetic lattice. The magnetic microtraps are created by a perpendicularly magnetized, multi-layered structure of TbGdFeCo film integrated on to an atom chip, together with uniform bias magnetic fields. Clear signatures for the onset of quantum degeneracy in multiple sites of the the magnetic lattice are provided by in-situ site-resolved radio-frequency spectroscopy

P. Salas, M. Fortes, M. de Llano +2 more

Kornel Witkowski, T. K. Kopeć

Abstract The Bose–Einstein condensation (BEC) in three-dimensional (3D) anisotropic lattices is studied. We present theoretical results for the critical temperature for BEC, chemical potential, condensate fraction and relevant thermodynamic quantities like: internal energy, entropy, specific heat and compressibility as a function of anisotropy parameter being the ratio of the nearest-neighbor in-plane ( $$t_\parallel$$ t ‖ ) and out-of-plane ( $$t_\perp$$ t ⊥ ) hopping amplitudes. In particular, considered scenarios include weakly coupled two-dimensional (2D) planes ( $$t_\perp /t_\parallel \ll 1$$ t ⊥ / t ‖ ≪ 1 , relevant for layered structures) as well as a rod-like geometry of interacting one-dimensional (1D) chains ( $$t_\parallel /t_\perp \ll 1$$ t ‖ / t ⊥ ≪ 1 ). The impact of the dimensional crossover as the system is tuned away from a set of disconnected 2D layers, or traverses from a set of separate 1D chains to a regime where a fully isotropic 3D structure emerges is elucidated. Both numerical and analytic approaches are employed, (the latter in a form of series expansions involving $$t_\parallel ,t_\perp$$ t ‖ , t ⊥ amplitudes) for internal energy, entropy, specific heat and isothermal compressibility. The theoretical outcome of the present study may be of interest to a number of scenarios in solid-state physics, where the relevant quasi-particles are bosonic-like, as well as might be applicable to the physics of cold bosons loaded in artificially engineered 3D optical lattices.

Y. Imry, David J. Bergman, Leon Gunther

Liu Jing-yi

By using the local density approximation, Bose-Einstein condensation of Bose gas in the low dimensional space is investigated. The results show that when a proper external potential is taken, BEC may occur in the low dimensional space. The critical temperature Tc, the ground state fraction N0/N and the behaviour (jump or not) of the heat capacity C depend on the shape of the potential.