二维变拓扑势场中的竞争隧穿轨道作为量子分岔模型

具有两自旋和三自旋竞争相互作用的一维自旋模型的基态保真度分岔

Bifurcation in ground-state fidelity for a one-dimensional spin model with competing two-spin and three-spin interactions

利用基于无限矩阵乘积态表象的张量网络算法，研究了具有两自旋和三自旋竞争相互作用的一维量子自旋模型.该算法是一个适应维达尔的无限时间演化块抽取算法，涉及三个自旋相互作用的自旋不变的一维晶格自旋系统。计算了在几个选定的耦合常数值下每个格点的基态保真度，并揭示了它的分叉。我们成功地确定了临界点，并推导出局部序参量来表征传统的Ginzburg-Landau-Wilson范式中的不同阶段。

可积量子二聚体谱的经典分支现象

Manifestation of classical bifurcation in the spectrum of the integrable quantum dimer

我们分析了可积二聚体问题的经典和量子性质。经典的版本表现出在相空间中，这产生了置换对称性破缺轨迹和分界线的一个分支。量子分析产生了所有的隧穿率（分裂）的领导秩序的微扰。在半经典制度的数值精确对角化得到的本征值谱可以得出结论的分界线和相应的经典模型中的分歧的存在。

子奥希姆系统中量子临界性：超越传统自旋-玻色物理

Quantum criticality in sub-Ohmic systems with three competing terms: beyond conventional spin-boson physics

研究子奥希姆浴中自旋-玻色模型的量子相变，揭示在低频谱指数下存在丰富的相图，发现新的U(1)对称相及奇宇称相，提出多阶段量子相变序列。

Dynamic zero modes of Dirac fermions and competing singlet phases of antiferromagnetic order

In quantum spin systems, singlet phases often develop in the vicinity of an antiferromagnetic order. Typical settings for such problems arise when itinerant fermions are also present. In this work, we develop a theoretical framework for addressing such competing orders in an itinerant system, described by Dirac fermions strongly coupled to an O(3) nonlinear sigma model. We focus on two spatial dimensions, where upon disordering the antiferromagnetic order by quantum fluctuations the singular tunneling events also known as (anti)hedgehogs can nucleate competing singlet orders in the paramagneti…

Optimization with delay-induced bifurcations

Optimization is finding the best solution, which mathematically amounts to locating the global minimum of some cost function. Optimization is traditionally automated with digital or quantum computers, each having their limitations and none guaranteeing an optimal solution. Here, we conceive a principle behind optimization based on delay-induced bifurcations, which is potentially implementable in non-quantum analog devices. Often, optimization techniques are interpreted via a particle moving in multi-well energy landscape and to prevent confinement to a non-global minima they should incorporate…

Quantum chaos, thermalization and tunneling in an exactly solvable few body system

Exactly solvable models that exhibit quantum signatures of classical chaos are both rare as well as important - more so in view of the fact that the mechanisms for ergodic behavior and thermalization in isolated quantum systems and its connections to non-integrability are under active investigation. In this work, we study quantum systems of few qubits collectively modeled as a kicked top, a textbook example of quantum chaos. In particular, we show that the 3 and 4 qubit cases are exactly solvable and yet, interestingly, can display signatures of ergodicity and thermalization. Deriving analytic…