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arXiv 0903.2552cond-mat.mes-hall
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准一维环阱中玻色-约瑟夫森结的量子涨落

Quantum fluctuations of a Bose-Josephson junction in a quasi-one-dimensional ring trap

N. Didier, A. Minguzzi, F. W. J. Hekking

摘要:

本文用Luttinger液体方法研究了玻色-约瑟夫森结的量子涨落。对于无限势垒,我们研究了单粒子和两粒子静态关联函数。对于单体密度矩阵,我们得到不同的幂律衰减取决于探测点的位置相对于位置的障碍。这种准长程序原则上可以用干涉测量实验探测。相应的动量分布在小动量也被证明是由障碍的存在下,并显示普遍的幂律行为预期的相互作用的一维流体的影响。我们还评估了粒子密度分布,并通过与Tonks-Girardeau极限下的精确结果进行比较,我们确定了Luttinger液体理论的非普适参数。一旦参数是从单体性质确定的,我们评估的密度-密度关联函数,发现一个显着的协议之间的Luttinger液体的预测和Tonks-Girardeau极限的确切结果,即使在Friedel振荡的长度尺度的特征的行为的密度-密度关联函数在中间距离。最后,对于一个大的,但有限的障碍,我们使用的单体关联函数来估计量子涨落的势垒高度的重整化的效果,找到减少的有效约瑟夫森耦合能量,这取决于环的长度和相互作用强度。

英文摘要:

Using a Luttinger-liquid approach we study the quantum fluctuations of a Bose-Josephson junction, consisting of a Bose gas confined to a quasi one-dimensional ring trap which contains a localized repulsive potential barrier. For an infinite barrier we study the one-particle and two-particle static correlation functions. For the one-body density-matrix we obtain different power-law decays depending on the location of the probe points with respect to the position of the barrier. This quasi-long range order can be experimentally probed in principle using an interference measurement. The corresponding momentum distribution at small momenta is also shown to be affected by the presence of the barrier and to display the universal power-law behavior expected for an interacting 1D fluid. We also evaluate the particle density profile, and by comparing with the exact results in the Tonks-Girardeau limit we fix the nonuniversal parameters of the Luttinger-liquid theory. Once the parameters are determined from one-body properties, we evaluate the density-density correlation function, finding a remarkable agreement between the Luttinger liquid predictions and the exact result in the Tonks-Girardeau limit, even at the length scale of the Friedel-like oscillations which characterize the behavior of the density-density correlation function at intermediate distance. Finally, for a large but finite barrier we use the one-body correlation function to estimate the effect of quantum fluctuations on the renormalization of the barrier height, finding a reduction of the effective Josephson coupling energy, which depends on the length of the ring and on the interaction strength.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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