论文标题
可调的解剖量子临界和不同价值固体相的相互作用
Tunable deconfined quantum criticality and interplay of different valence-bond solid phases
论文作者
论文摘要
我们使用量子蒙特卡洛模拟研究量子$ s = 1/2 $旋转模型，具有竞争性多旋转相互作用。我们发现柱状价值键固体（CVB）和NéelAntiferromagnet（AFM）之间的量子相变，如在解剖学量子量点的情况下，以及AFM和交错的价值 - 固体（SVB）之间的过渡。通过连续改变参数，SVB-AFM和AFM--CVBS边界合并为直接的SVBS--CVBS跃迁。与以前具有推定脱合型AFM--CVBS过渡的模型不同，例如，在我们的扩展$ j $ q $型号中，在我们的扩展$ j $ - $ q $型号中，具有竞争性的CVB和SVB诱导术语，可以从连续的一阶调整过渡。当过渡连续时，我们发现显微镜上的$ z_4 $对称CVBS订单参数的预期出现U（1）对称性。相反，当过渡变为一阶时，时钟状$ z_4 $波动就不存在，并且没有紧急的更高对称性。我们认为，SVBS相的受限旋子类似于分形式。我们还提供了具有相似相图的SU（3）对称模型的结果。新的模型家族可以用作进一步研究与解剖量子关键性及其相关的紧密对称性有关的开放问题的有用工具。
We use quantum Monte Carlo simulations to study a quantum $S=1/2$ spin model with competing multi-spin interactions. We find a quantum phase transition between a columnar valence-bond solid (cVBS) and a Néel antiferromagnet (AFM), as in the scenario of deconfined quantum-critical points, as well as a transition between the AFM and a staggered valence-bond solid (sVBS). By continuously varying a parameter, the sVBS--AFM and AFM--cVBS boundaries merge into a direct sVBS--cVBS transition. Unlike previous models with putative deconfined AFM--cVBS transitions, e.g., the standard $J$-$Q$ model, in our extended $J$-$Q$ model with competing cVBS and sVBS inducing terms the transition can be tuned from continuous to first-order. We find the expected emergent U(1) symmetry of the microscopically $Z_4$ symmetric cVBS order parameter when the transition is continuous. In contrast, when the transition changes to first-order the clock-like $Z_4$ fluctuations are absent and there is no emergent higher symmetry. We argue that the confined spinons in the sVBS phase are fracton-like. We also present results for an SU(3) symmetric model with a similar phase diagram. The new family of models can serve as a useful tool for further investigating open questions related to deconfined quantum criticality and its associated emergent symmetries.
