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arXiv 0802.0728cond-mat.othercond-mat.supr-con
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玻色-爱因斯坦凝聚体中势垒附近准粒子流的反常增强

Anomalous enhancement of quasiparticle current near a potential barrier in a Bose-Einstein condensate

S. Tsuchiya, Y. Ohashi

备注：
4 pages, 3 figures, published version
发表信息：
Phys. Rev. A 78, 013628 (2008)
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摘要：

本文研究了玻色-爱因斯坦凝聚体中Bogoliubov声子的隧穿性质。我们发现，由于凝聚体提供的过剩电流，Bogoliubov声子携带的准粒子电流$J_{\rm q}$在势垒附近出现异常增强。这种效应导致Kovrizhin { \it et al.}发现的低能区准粒子透射几率增加。我们还表明，准粒子电流扭曲的相位的凝聚波函数跨越障碍，导致有限的约瑟夫森超导$J_{\rm s}$通过障碍。该感应超电流以与准粒子电流相反的方向流动，从而抵消了$J_{\rm q}$的增强并保持总电流$J=J_{\rm q}+J_{\rm s}$。

英文摘要：

We investigate tunneling properties of Bogoliubov phonons in a Bose-Einstein condensate. We find the anomalous enhancement of the quasiparticle current $J_{\rm q}$ carried by Bogoliubov phonons near a potential barrier, due to the supply of the excess current from the condensate. This effect leads to the increase of quasiparticle transmission probability in the low energy region found by Kovrizhin {\it et al.}. We also show that the quasiparticle current twists the phase of the condensate wavefunction across the barrier, leading to a finite Josephson supercurrent $J_{\rm s}$ through the barrier. This induced supercurrent flows in the opposite direction to the quasiparticle current so as to cancel out the enhancement of $J_{\rm q}$ and conserve the total current $J=J_{\rm q}+J_{\rm s}$.

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