As proposed to describe putative continuous phase transitions between two ordered phases, the deconfined quantum critical point (DQCP) goes beyond the prevalent Landau-Ginzburg-Wilson (LGW) paradigm since its critical theory is not expressed in terms of the order parameters characterizing either state, but involves fractionalized degrees of freedom and an emergent symmetry. So far, great efforts have been spent on its equilibrium properties, but the nonequilibrium properties therein are largely unknown. Here we study the nonequilibrium dynamics of the DQCP via the imaginary-time evolution in the two-dimensional (2D) J-Q$_3$ model. We discover fascinating nonequilibrium scaling behaviors hinging on the process of fractionization and the dynamics of emergent symmetry associated with two length scales. Our findings not only constitute a new realm of nonequilibrium criticality in DQCP, but also offer a controllable knob by which to investigate the dynamics in strongly correlated systems.
Emergent symmetry is one of the characteristic phenomena in deconfined quantum critical point (DQCP). As its nonequilibrium generalization, the dual dynamic scaling was recently discovered in the nonequilibrium imaginary-time relaxation dynamics in the DQCP of the $J$-$Q_3$ model. In this work, we study the nonequilibrium imaginary-time relaxation dynamics in the $J$-$Q_2$ model, which also hosts a DQCP belonging to the same equilibrium universality class. We not only verify the universality of the dual dynamic scaling at the critical point, but also investigate the breakdown and the vestige o…
Nonequilibrium Dynamics of Dirac Quantum Criticality in Imaginary Time
Sun Yat-Sen University（中山大学）；Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所及凝聚态物理北京国家实验室）；University of Chinese Academy of Sciences（中国科学院大学）；School of Physics and Materials Science, Guangzhou University（广州大学物理与材料科学学院）
Preempting Fermion Sign Problem: Unveiling Quantum Criticality through Nonequilibrium Dynamics in Imaginary Time
School of Physics, Sun Yat-sen University（中山大学物理学院）；Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-sen University（中山大学磁电物理与器件广东省重点实验室）；Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所（北京凝聚态物理国家研究中心））；University of Chinese Academy of Sciences（中国科学院大学）
We develop a nonequilibrium increment method to compute the Rényi entanglement entropy and investigate its scaling behavior at the deconfined critical (DQC) point via large-scale quantum Monte Carlo simulations. To benchmark the method, we first show that at an conformally-invariant critical point of O(3) transition, the entanglement entropy exhibits universal scaling behavior of area law with logarithmic corner corrections and the obtained correction exponent represents the current central charge of the critical theory. Then we move on to the deconfined quantum critical point, where although …
Photo-induced nonequilibrium response in underdoped YBa$_2$Cu$_3$O$_{6+x}$ probed by time-resolved terahertz spectroscopy
强激光脉冲最近已经成为一种工具，可以在复杂的量子材料中调节不同的顺序。在众多的光诱导现象中，铜氧化物中远高于平衡转变温度的瞬态超导现象尤其引人注目。这些实验的关键是特定声子模式的共振泵浦，人们认为这可以通过抑制竞争阶数或稍微修改结构来诱导超导相位相干性。本文对欠掺杂$_2$ O $_{6+x}$的光致非平衡响应进行了全面的研究。我们发现，在光激发下，超导态的约瑟夫森等离子体边缘最初伴随着准粒子激发而消失，随后在短时间内以低于静态等离子体边缘的频率重新出现。在正常状态下，增强或较弱的边缘状形状确实是由泵浦脉冲引起的反射光谱伴随着同时上升的实部和虚部的电导率。我们比较了近红外和中红外激发的泵浦诱导效应，并排除了声子泵浦作为上述光诱导效应的一种情况。我们进一步阐述了正常状态下的瞬态响应不太可能用光致超导来解释。
Non-commutative Dynamic Approaches to the Kibble-Zurek Scaling Limit with an Initial Gapless Order
Westlake University（西湖大学）；Westlake Institute for Advanced Study（西湖高等研究院）；Anhui University of Technology（安徽工业大学）；Hunan University（湖南大学）；Sun Yat-sen University（中山大学）
