Probing XY phase transitions in a Josephson junction array with tunable frustration
Probing XY phase transitions in a Josephson junction array with tunable frustration
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DOI：
10.1103/physrevb.102.094509
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发表时间：
2020-09-10
影响因子：
3.7
通讯作者：
Nakamura, Y.
中科院分区：
文献类型：
--
作者：
Cosmic, R.;Kawabata, K.;Nakamura, Y.
Berezinskii，Kosterlitz和Wavelless的开创性理论工作提出了一种由拓扑激发驱动的凝聚态相变的范式。这些转变已被广泛研究的背景下，二维XY模型耦合罗盘，并产生了兴趣的背景下，量子模拟。在这里，我们使用一个电路量子电动力学架构来研究工程XY模型的关键行为，通过他们的动态响应。特别地，我们不仅研究了未阻挫的情况，而且还研究了完全阻挫的情况，这导致了与自旋旋转[U（1）]和离散手征（Z（2））对称性相关的增强的简并性。在挫折的情况下，过渡的性质对理论研究提出了挑战，而直接的实验探测仍然难以捉摸。在这里，我们确定的过渡温度为未受挫和完全受挫XY模型探测约瑟夫森结阵列接近平衡，使用弱微波激发和测量的温度依赖性的有效阻尼从复杂的反射系数。我们认为，我们的探测技术主要是敏感的U（1）部分的动态。
The seminal theoretical works of Berezinskii, Kosterlitz, and Thouless presented a paradigm for phase transitions in condensed matter that are driven by topological excitations. These transitions have been extensively studied in the context of two-dimensional XY models-coupled compasses-and have generated interest in the context of quantum simulation. Here, we use a circuit quantum-electrodynamics architecture to study the critical behavior of engineered XY models through their dynamical response. In particular, we examine not only the unfrustrated case but also the fully frustrated case which leads to enhanced degeneracy associated with the spin rotational [U(1)] and discrete chiral (Z(2)) symmetries. The nature of the transition in the frustrated case has posed a challenge for theoretical studies while direct experimental probes remain elusive. Here we identify the transition temperatures for both the unfrustrated and fully frustrated XY models by probing a Josephson junction array close to equilibrium using weak microwave excitations and measuring the temperature dependence of the effective damping obtained from the complex reflection coefficient. We argue that our probing technique is primarily sensitive to the dynamics of the U(1) part.