The quantum breakdown of superconductivity (QBS) is the reverse, comprehensive approach to the appearance of superconductivity. A quantum phase transition from superconducting to insulating states tuned by using nonthermal parameters is of fundamental importance to understanding the superconducting (SC) phase but also to practical applications of SC materials. However, the mechanism of the transition to a nonzero resistive state deep in the SC state is still under debate. Here, we report a systematic study of MgB₂ bilayers with different thickness ratios for undamaged and damaged layers fabricated by low-energy iron-ion irradiation. The field-induced QBS is discovered at a critical field of 3.2 Tesla (=H_c), where the quantum percolation model best explains the scaling of the magnetoresistance near H_c. As the thickness of the undamaged layer is increased, strikingly, superconductivity is recovered from the insulating state associated with the QBS, showing that destruction of quantum phase coherence among Cooper electron pairs is the origin of the QBS.

超导量子击穿 (QBS) 是超导出现的反向综合方法。通过使用非热参数调节从超导状态到绝缘状态的量子相变对于理解超导 (SC) 相以及 SC 材料的实际应用具有根本重要性。然而，过渡到 SC 状态深处的非零电阻状态的机制仍在争论中。在这里，我们报告了对通过低能铁离子辐照制造的未损坏和损坏层具有不同厚度比的 MgB ₂双层的系统研究。在 3.2 特斯拉 (= H _c)，其中量子渗流模型最好地解释了H _c附近磁阻的缩放。随着未损坏层的厚度增加，令人惊讶的是，超导性从与 QBS 相关的绝缘状态中恢复，表明库珀电子对之间的量子相相干性破坏是 QBS 的起源。