弹道-局域化动力学作为约瑟夫森结量子相变的特征
Ballistic-to-Localized Dynamics as Signature of Quantum Phase Transition in Josephson Junction
- Università di Napoli Federico II（那不勒斯费德里科二世大学）
- INFN, Sezione di Napoli（意大利国家核物理研究所那不勒斯分部）
- SPIN-CNR（凝聚态物理特殊相互作用中心研究所）
- The Abdus Salam International Center for Theoretical Physics (ICTP)（阿卜杜斯·萨拉姆国际理论物理中心）
- RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所涌现物质科学中心）
- Fundamental Quantum Science Program (FQSP), TRIP Headquarters, RIKEN（理化学研究所量子科学计划总部）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
该研究通过数值技术探究小电容约瑟夫森结在不同耗散 regime 下的行为，发现欧姆耗散强度增加会驱动 Berezinskii-Kosterlitz-Thouless 量子相变，不同耗散 regime 的相变特性存在差异，且欧姆 regime 下动力学呈弹道-局域化变化。
中文摘要 AI 辅助
我们采用最先进的数值技术，研究量子相位涨落和准粒子隧穿如何影响小电容约瑟夫森结在欧姆、亚欧姆和超欧姆耗散 regime 下的行为。我们表明，增加欧姆耗散强度会在热力学平衡中驱动 Berezinskii-Kosterlitz-Thouless 量子相变。偏离欧姆行为会深刻改变这一情况：超欧姆 regime 无相位转变，而亚欧姆 regime 呈现连续二级相变，与自旋-玻色子模型的普适类一致。在欧姆 regime 内，实频率线性响应计算显示，相位粒子不会发生通常假设的扩散-局域化交叉，相反，有限电阻会逐步抑制奇异的零频响应，产生动力学上的弹道-局域化变化。在有限频率下，与环境的耦合会在电荷响应中产生长寿命激发，随着亚间隙和分流电阻降低，该激发会演变为共振。
英文摘要
Using state-of-the-art numerical techniques, we investigate how quantum phase fluctuations and quasiparticle tunneling shape the behavior of a small-capacitance Josephson junction across Ohmic, sub-Ohmic, and super-Ohmic dissipation regimes. We show that increasing the Ohmic dissipation strength drives a Berezinskii-Kosterlitz-Thouless quantum phase transition at thermodynamic equilibrium. Deviations from Ohmic behavior profoundly alter this scenario: the super-Ohmic regime exhibits no phase transition, whereas the sub-Ohmic regime displays a continuous second-order transition, consistent with the universality classes of the spin-boson model. Within the Ohmic regime, real-frequency linear-response calculations reveal that the phase particle does not undergo the commonly assumed diffusive-to-localized crossover. Instead, finite resistance progressively suppresses the singular zero-frequency response, producing a ballistic-to-localized change in the dynamics. At finite frequencies, coupling to the environment generates a long-lived excitation in the charge response, which evolves into a resonance as the subgap and shunt resistances are reduced.
