标题： 纠缠阵列中的集体量子相位 显示英文标题

标题： Collective quantum phases in frustrated arrays of Josephson junctions

摘要： 我们研究在小量子约瑟夫森结的受挫锯齿形阵列中出现的集体量子相和量子相变。 受挫是通过将$0$和$\pi$量子约瑟夫森结周期性排列引入的，其约瑟夫森耦合能$\alpha E_\mathrm{J}$具有不同的符号，$-1\leq \alpha \leq 1$。 系统势能景观的复杂性由受挫参数$f=(1-\alpha)/2$控制。 在非受挫区域（$f<f_\mathrm{cr}=0.75$）中，势能具有单一全局最小值，在受挫区域（$f>f_\mathrm{cr}=0.75$）中则具有大量相等的最小值。 我们研究相干量子区域，并识别出几种集体量子相：在非受挫区域中的无序（绝缘）相和有序（超导）相，以及在受挫区域中涡旋和反涡旋的高度纠缠模式。 这些集体量子相由几个物理参数控制：挫折$f$，约瑟夫森耦合以及结和岛的电荷能。 我们通过表征受挫约瑟夫森结阵列的局域磁化率的时空分辨量子力学关联函数，绘制出控制参数相图。 显示英文摘要

摘要： We study collective quantum phases and quantum phase transitions occurring in frustrated sawtooth arrays of small quantum Josephson junctions. Frustration is introduced through the periodic arrangement of $0$- and $\pi$- Josephson junctions with the Josephson coupling energies $\alpha E_\mathrm{J}$ of different signs, $-1\leq \alpha \leq 1$. The complexity of the potential landscape of the system is controlled by the frustration parameter $f=(1-\alpha)/2$. The potential energy has a single global minimum in the non-frustrated regime ($f<f_\mathrm{cr}=0.75$) and a macroscopic number of equal minima in the frustrated regime ($f>f_\mathrm{cr}=0.75$). We address the coherent quantum regime and identify several collective quantum phases: disordered (insulating) and ordered (superconducting) phases in the non-frustrated regime, as well as highly entangled patterns of vortices and anti-vortices in the frustrated regime. These collective quantum phases are controlled by several physical parameters: the frustration $f$, the Josephson coupling, and the charging energies of junctions and islands. We map the control parameter phase diagram by characterizing the quantum dynamics of frustrated Josephson junction arrays by spatially and temporally resolved quantum-mechanical correlation function of the local magnetization.