论文标题
在约瑟夫森连接阵列中探测xy相变的挫败感
Probing XY phase transitions in a Josephson junction array with tunable frustration
论文作者
论文摘要
Berezinskii,Kosterlitz和Thouless的开创性理论作品提出了一个新的范式,用于由拓扑激发驱动的凝结物质中的相变。这些过渡已在二维XY模型(耦合指南针)的背景下进行了广泛的研究,并在量子模拟的背景下引起了兴趣。在这里,我们使用电路量子 - 电动力学结构来通过其动力响应来研究工程XY模型的临界行为。特别是,我们不仅检查了未施工的情况,而且还检查了完全伪造的情况,这会导致与自旋旋转[U $(1)$]和离散手性($ Z_2 $)对称性相关的变性。在沮丧的情况下,过渡的性质对理论研究提出了挑战,而直接实验探测仍然难以捉摸。在这里,我们通过使用弱微波激励接近平衡的约瑟夫森连接阵列,并测量从复杂反射系数获得的有效阻尼的温度依赖性来探测接近平衡的Josephson结阵列,以确定未施工和完整XY模型的过渡温度。我们认为我们的探测技术主要对U $(1)$零件的动态敏感。
The seminal theoretical works of Berezinskii, Kosterlitz, and Thouless presented a new 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.