• Title, Summary, Keyword: Bose-Einstein condensate

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Dynamics of a Bose-Einstein Condensate on Changing Speeds of an Atomchip Trap Potential

  • Kim, Seung Jin;Noh, Jae June;Kim, Min Seok;Lee, Jin Seung;Yu, Hoon;Kim, Jung Bog
    • Journal of the Optical Society of Korea
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    • v.18 no.6
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    • pp.633-638
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    • 2014
  • We report experimental behaviors of condensed $^{87}Rb$ atoms responding to changes in the trap potential of the atomchip. The two-types of adiabatic and non-adiabatic overall changes were implemented by changing the ramp-down speed of the chip-wire current, which can dominantly modify the one-axis magnetic field gradient. Under the adiabatic process, a pure condensate stayed in the initial spin state and collectively oscillated with both monopole and dipole modes, while an atomic cloud above the critical temperature exhibited sound waves in a dense ultracold gas. On the other hand, Bose-Einstein condensate atoms with non-adiabatic perturbation were split into spatially different positions by spin states through spin-flip. We investigated the split ratio among spin states depending on final evaporation frequency. Potential changes, of course, cause collective oscillations regardless of the changing process.

NOTE ON THE GROUND STATES OF TWO-COMPONENT BOSE-EINSTEIN CONDENSATES WITH AN INTERNAL ATOMIC JOSEPHSON JUNCTION

  • Lu, Zhongxue;Liu, Zuhan
    • Bulletin of the Korean Mathematical Society
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    • v.50 no.5
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    • pp.1441-1450
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    • 2013
  • In this paper, we consider two-component Bose-Einstein condensates with an internal atomic Josephson junction in the general case, i.e., 0 < p < $\frac{2}{(d-2)^+}$. We prove existence and uniqueness results for the ground states, and obtain some properties of the ground states with large parameters.

Radial basis function collocation method for a rotating Bose-Einstein condensation with vortex lattices

  • Shih, Y.T.;Tsai, C.C.;Chen, K.T.
    • Interaction and multiscale mechanics
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    • v.5 no.2
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    • pp.131-144
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    • 2012
  • We study a radial basis function collocation method (RBFCM) to discretize a coupled nonlinear Schr$\ddot{o}$dinger equation (CNLSE) that governs a two dimensional rotating Bose-Einstein condensate (BEC) with an angular momentum rotation term. We exploit a RBFCM-continuation method (RBFCM-CM) to trace the solution curve of the CNLSE. We compare the performance of the RBFCM-CM with the FEM-CM. We observe that the RBFCM-CM is very robust in a coarse grid for resolving the ground state solution with many vortices when the angular momentum rotation is close to the limit. Numerical results demonstrate the efficiency and accuracy of the RBFCM-CM for computing the superfluid density of the ground level of the BEC.

Quantum Entanglement of Dark Matter

  • Lee, Jae-Weon
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1596-1602
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    • 2018
  • We suggest that the dark matter in the universe has quantum entanglement if the dark matter is a Bose-Einstein condensation of ultra-light scalar particles. In this theory, any two regions of a galaxy are quantum entangled due to the quantum nature of the condensate. We calculate the entanglement entropy of a typical galactic halo, which turns out to be at least O(ln(M/m)), where M is the mass of the halo and m is the mass of a dark matter particle. The entanglement can be inferred from the rotation curves of the galaxy or the interference patterns of the dark matter density.

Electromagnetically Induced Transparency with Hyperfine Structure (사다리형 전자기 유도 투과에서의 초미세 구조)

  • Moon, Han-Sub;Lee, Rim;Lee, Won-Kyu;Seo, Ho-Sung;Kim, Joong-Bok
    • Proceedings of the Optical Society of Korea Conference
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    • pp.206-207
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    • 2003
  • 전자기 유도 투과(electromagnetically induced transparency ; EIT)는 원자의 공명 진동수를 갖는 조사광이 원자 매질을 통과할 때, 강한 결합광에 의한 효과로 매질에 흡수되지 않고 투과하는 양자 간섭 효과로써 원자결맞음 현상의 가장 대표적인 현상 중의 하나이다. EIT 현상은 Boller 등에 의해서 고출력 펄스 레이저를 이용하여 Strontium 증기에서 처음 관측된 이후, 여러 가지 원자와 분자의 증기 셀, 원자 빔, 고체, 냉각된 원자, 그리고 BEC(Bose Einstein condensate)상태에서 다양한 연구들이 이루어지고 있다. (중략)

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