Kozub V I, Lopatin A V, Vinokur V M
Material Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Phys Rev Lett. 2003 Jun 6;90(22):226805. doi: 10.1103/PhysRevLett.90.226805. Epub 2003 Jun 4.
We investigate the Josephson transport through a thin semiconductor barrier containing impurity centers with the on-site Hubbard interaction u of an arbitrary sign and strength. We find that in the case of the repulsive interaction the Josephson current changes sign with the temperature increase if the energy of the impurity level epsilon (measured from the Fermi energy of superconductors) falls in the interval (-u,0). We predict strong temporal fluctuations of the current if only a few centers are present within the junction. In the case of the attractive impurity potential (u<0) and at low temperatures, the model is reduced to the effective two level Hamiltonian allowing thus a simple description of the nonstationary Josephson effect in terms of pair tunneling processes.
我们研究了通过包含具有任意符号和强度的在位哈伯德相互作用(u)的杂质中心的薄半导体势垒的约瑟夫森输运。我们发现，在排斥相互作用的情况下，如果杂质能级(\epsilon)（从超导体的费米能测量）的能量落在区间((-u,0))内，约瑟夫森电流会随着温度升高而改变符号。我们预测，如果结内仅存在少数中心，电流会有强烈的时间波动。在吸引杂质势((u<0))且低温的情况下，该模型简化为有效的两能级哈密顿量，从而可以根据对隧穿过程对非平稳约瑟夫森效应进行简单描述。
