Bose - einstein condensate

Trạng thái ngưng tụ Bose - Einstein được tạo ra đầu tiên trên thế giới (BEC - Bose - Einstein condensate) từ những nguyên tử lạnh năm 1995. Điều này có ý nghĩa lớn là tạo nên một dạng vật chất mới trong đó các hạt bị giam chung trong trạng thái ở năng lượng thấp nhất, đã mở ra nhiều triển vọng nghiên cứu trong Vật lý. Đây là lĩnh vực đã và đang thu hút được sự quan tâm của nhiều nhà Vật lý trên thế giới.

47p capheviahe29 17-03-2021 15 3   Download

The analytical expressions for the wave functions of two-component Bose-Einstein Condensates are derived by means of the Gross-Pitaevskii equations in linear approximation. Based on the Bernoulli equation the shape of the interface and the dispersion relations for both phonon and ripplonare studied.

6p tamynhan5 10-12-2020 12 1   Download

Based on the Cornwall-Jackiw-Tomboulis effective action approach, a theoretical formalism is established to study the hydrodynamic instabilities in two-component condensates of Bose gases. The effective potential is found in the Hartree-Fock approximation and this quantity is then used to derive the expression for the pressure, which depends on particle densities.

8p tamynhan9 02-12-2020 13 4   Download

The ripplon modes of two segregated Bose-Einstein condensates (BECs) confined by one and two hard walls are respectively studied by means of the hydrodynamic approach within the Gross-Pitaevskii (GP) theory. For the system at rest we find that due to the spatial restriction the dispersion relations are of the form ω ∼ k 2 in low momentum limit for both cases, while for the system in motion parallel to the interface the dispersion relations for both cases are ω ∼ k at low momentum limit and, furthermore, the system becomes unstable.

8p thuyliebe 08-10-2018 24 0   Download

Besides introduction and conclusion, this thesis consists of 3 chapters. Chapter 1. Overview of Bose-Einstein condensate. Theory of BECs.Chapter 2. Interfacial tension and wetting phase transition in the system of BECs limited by one hard wall. Chapter 3. Finite-size effects of interfacial tension in the system of BECs limited by two hard walls.

28p cumeo2009 24-07-2018 43 2   Download