Population dynamics of a Bose gas near saturation.
Population dynamics of a Bose gas near saturation.
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接近饱和的玻色气体的粒子群动态。
DOI：
10.1103/physrevb.39.4030
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
J. Wolfe
中科院分区：
文献类型：
--
作者：
D. Snoke;J. Wolfe
在低密度下，玻色子气体在几个特征散射时间内达到经典的能量平衡分布。在足够高的密度下，受激辐射开始发挥作用，增加了向低能态散射的速率。这就产生了著名的玻色-爱因斯坦平衡分布。在本文中，我们通过数值计算表明，对于弱相互作用的玻色气体，达到平衡玻色-爱因斯坦分布所需的特征散射次数随着简并度的增加而增加。然而，我们发现受激辐射大大缩短了简并气体的特征散射时间，最终结果是平衡时间可以与经典情况相当。这些结果与最近产生激子简并玻色分布的实验有关。这些实验的一个基本问题是玻色-爱因斯坦凝聚能否在粒子生命周期内发生。我们的计算表明可能会发生凝结。我们还在本文中表明，激子-声子相互作用不会显著增加接近凝结的速率。
At low density a gas of bosons achieves a classical equilibrium distribution of energies within just a few characteristic scattering times. At sufficiently high densities, stimulated emission comes into play, increasing the rate of scattering into low-energy states. This results in the well-known Bose-Einstein equilibrium distribution. In this paper we show—by numerical calculation—that for a weakly interacting Bose gas the number of characteristic scattering times required to achieve an equilibrium Bose-Einstein distribution increases with increasing degeneracy. However, we find that the characteristic scattering time for the degenerate gas is significantly shortened by the stimulated emission, with the net result that equilibration times may be comparable to the classical case. These results have a bearing on recent experiments that produced degenerate Bose distributions of excitons. A basic question from these experiments is whether Bose-Einstein condensation can occur within the particle lifetime. Our calculations indicate that condensation may take place. We also show in this paper that exciton-phonon interactions will not significantly increase the rate of approach to condensation.