arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.15648cond-mat.mes-hallcond-mat.supr-con
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电子-玻色子相互作用诱导超导体电导的粒子-空穴对称破缺

Electron-boson-interaction induced particle-hole symmetry breaking of conductance into subgap states in superconductors

F. Setiawan, Jay D. Sau

摘要:

超导体中电导进入亚能隙态的粒子-空穴对称性是超导体的非相互作用平均场论的一个基本结论。这种PHS的断裂归因于非相互作用机制,即,准粒子中毒(quasiparticle poisoning,QP),一个对超导体量子比特相干性有害的过程。在这里,我们证明了超导体中普遍存在的电子-玻色子相互作用也可以打破亚带隙电导的PHS。我们研究了这种耦合对PHS的亚带隙电导在超导体中使用的速率方程和Keldysh形式主义,这有不同的制度的有效性。在这两个制度中,我们发现,这种耦合引起的粒子空穴$asymmetry$的子带隙电导增加,增加耦合强度,增加子带隙态粒子空穴含量的不平衡和降低温度。我们提出的机制是通用的,甚至适用于实验中的亚间隙电导小灵通打破不能归因于QP。

英文摘要:

Particle-hole symmetry (PHS) of conductance into subgap states in superconductors is a fundamental consequence of a noninteracting mean-field theory of superconductivity. The breaking of this PHS has been attributed to a noninteracting mechanism, i.e., quasiparticle poisoning (QP), a process detrimental to the coherence of superconductor-based qubits.Here, we show that the ubiquitous electron-boson interactions in superconductors can also break the PHS of subgap conductances. We study the effect of such couplings on the PHS of subgap conductances in superconductors using both the rate equation and Keldysh formalism, which have different regimes of validity. In both regimes, we found that such couplings give rise to a particle-hole $asymmetry$ in subgap conductances which increases with increasing coupling strength, increasing subgap-state particle-hole content imbalance and decreasing temperature. Our proposed mechanism is general and applies even for experiments where the subgap-conductance PHS breaking cannot be attributed to QP.

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