AI 中文总结
研究周期驱动二聚化自旋链中的疤痕离散时间晶体相，利用量子多体疤痕实现弱遍历破缺，其寿命随系统尺寸增长后会因杂化饱和，为相关动力学相互作用提供综合框架。
AI 中文摘要
我们研究周期驱动二聚化自旋链中疤痕离散时间晶体（SDTC）相的出现。尽管一般相互作用的Floquet系统本应按照本征态热平衡假设（ETH）热化，但我们证明该系统存在量子多体疤痕（QMBS），诱导出弱遍历破缺的区域。通过分析Floquet能级统计、纠缠熵和本征态保真度，我们在原本热谱中识别出由半泊松统计表征的低纠缠态流形。这些疤痕态支持具有周期加倍的稳健次谐波振荡，标志着离散时间平移对称性的自发破缺。我们表明SDTC响应对多种初态构型具有稳健性，证明其在精细调谐条件之外仍具稳定性。有限尺寸标度分析显示，在精确对角化计算可达的范围内，时间晶体寿命随系统尺寸增大而增长；但借助近似多体疤痕的一般现象学，我们预期Floquet疤痕与热连续体的杂化最终会限制该增长，使寿命在超出当前数值可达范围的系统尺寸下达到饱和。这将SDTC表征为长寿命的亚稳动力学区域，而非严格稳定的热力学相，为理解无无序系统中周期驱动与受限多体动力学的相互作用提供了综合框架。
英文摘要
We investigate the emergence of a scarred discrete time crystal (SDTC) phase in a periodically driven dimerized spin chain. While generic interacting Floquet systems are expected to thermalize according to the eigenstate thermalization hypothesis (ETH), we demonstrate that this system hosts quantum many-body scars (QMBS) that induce a regime of weak ergodicity breaking. Through an analysis of Floquet level statistics, entanglement entropy, and eigenstate fidelity, we identify a manifold of low-entanglement states characterized by semi-Poisson statistics embedded within an otherwise thermal spectrum. These scarred states support robust subharmonic oscillations with period doubling, signaling the spontaneous breaking of discrete time-translation symmetry. We show that the SDTC response is robust against a variety of initial state configurations, demonstrating its stability beyond fine-tuned conditions. A finite-size scaling analysis reveals that the time-crystalline lifetime grows with system size within the range accessible to our exact-diagonalization calculations. However, drawing on the general phenomenology of approximate many-body scars, we expect that hybridization between Floquet scars and the thermal continuum will eventually curtail this growth, causing the lifetime to saturate at system sizes beyond our current numerical reach. This characterizes the SDTC as a long-lived metastable dynamical regime rather than a strictly stable thermodynamic phase, providing a comprehensive framework for understanding the interplay between periodic driving and constrained many-body dynamics in disorder-free systems.
Comments13 pages, 15 Figures
