In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor–bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers. By monitoring the evolved superconducting gaps and diminished coherence peaks in the single-quasiparticle density of states, we link the destruction of the superconducting state and the emergence of bosonic dirty metallic state to breaking of the global phase coherence and persistence of the localized Cooper pairs. The observed resistive bosonic phase transitions are well modeled using a series–parallel circuit in the framework of bosonic confinement and coherence.

中文翻译：

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无序纳米金刚石阵列中的玻色子约束和相干性

在无序的情况下，超导表现出与局部库珀对相关的短程特性，这些库珀对负责异常的相变和量子态（例如玻色子绝缘态）的出现。作为研究良好的均质无序超导体的补充，超导体-常态混合阵列为研究异常量子相变提供了颗粒无序程度的可调实现。在这里，我们研究了无序纳米金刚石阵列中超导体-玻色子的脏金属跃迁与晶格间距（范围为埃至微米）之间的弥散的函数。通过监视状态的单准粒子密度中演化的超导间隙和相干峰的减小，我们将超导态的破坏和玻色金属脏态的出现与整体相干性的破坏和局部库珀对的持久性联系起来。在玻色子约束和相干性的框架内，使用串联-并联电路很好地模拟了观察到的电阻性玻色子相变。