论文标题
DC在DC原子超导量子干扰装置中向AC约瑟夫森过渡
dc to ac Josephson transition in a dc atom superconducting quantum interference device
论文作者
论文摘要
我们分析了屏障运动对一对约瑟夫森连接中断的环形玻色子冷凝水的玻色式hamiltonian的影响。这种效果还显示出可以修改两种模式近似中玻色子场操作员运动的Heisenberg运动方程，其中可能会影响加速或重叠障碍的动力学的滞后贡献。通过研究能量格局作为秩序和控制参数的函数，我们确定了DC和AC Josephson Segimes的位置的图，以及所显示的临界点取决于连接位置。我们分析了直流向AC约瑟夫森过渡的绝热屏障轨迹，该轨迹导致最终均匀的速度或执行对称速度路径。我们表明，这种对称轨迹在达到临界点时可能会诱导高度滞后振荡的回程路径，类似于由AC策略中电阻流的作用引起的不足阻尼的磁滞回路。我们还考虑了连接两侧的有限相位差以及这种参数的临界特征所产生的非平衡初始条件。在所有情况下，都发现了GROSS-PITAEVSKII模拟与两模式结果之间的一个极好的一致性。
We analyze the effect of the barrier motion on the Bose-Hubbard Hamiltonian of a ring-shaped Bose-Einstein condensate interrupted by a pair of Josephson junctions, a configuration which is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). Such an effect is also shown to modify the Heisenberg equation of motion of the boson field operator in the two-mode approximation, where a hysteretic contribution that could affect the dynamics for accelerated or overlapping barriers is identified. By studying the energy landscape as a function of order and control parameters, we determine the diagram with the location of the dc and ac Josephson regimes, along with the critical points that are shown to depend on the junctions position. We analyze the dc to ac Josephson transition for adiabatic barrier trajectories that lead to a final uniform velocity, or which perform symmetric velocity paths. We show that such symmetric trajectories may induce, when reaching the critical point, highly hysteretic oscillating return paths within the dc regime, similar to the underdamped hysteresis loops arising from the action of a resistive flow in the ac regime. We also consider nonequilibrium initial conditions resulting from a finite phase difference on either side of the junctions, along with the critical features of such a parameter. An excellent agreement between the Gross-Pitaevskii simulations and the two-mode results is found in all cases.
