Mukhopadhyay S, Senior J, Saez-Mollejo J, Puglia D, Zemlicka M, Fink J M, Higginbotham A P
IST Austria, Klosterneuburg, Austria.
Nat Phys. 2023;19(11):1630-1635. doi: 10.1038/s41567-023-02161-w. Epub 2023 Aug 10.
Arrays of Josephson junctions are governed by a competition between superconductivity and repulsive Coulomb interactions, and are expected to exhibit diverging low-temperature resistance when interactions exceed a critical level. Here we report a study of the transport and microwave response of Josephson arrays with interactions exceeding this level. Contrary to expectations, we observe that the array resistance drops dramatically as the temperature is decreased-reminiscent of superconducting behaviour-and then saturates at low temperature. Applying a magnetic field, we eventually observe a transition to a highly resistive regime. These observations can be understood within a theoretical picture that accounts for the effect of thermal fluctuations on the insulating phase. On the basis of the agreement between experiment and theory, we suggest that apparent superconductivity in our Josephson arrays arises from melting the zero-temperature insulator.
约瑟夫森结阵列受超导性和排斥性库仑相互作用之间的竞争支配，并且当相互作用超过临界水平时，预计会表现出发散的低温电阻。在此，我们报告了对相互作用超过该水平的约瑟夫森阵列的输运和微波响应的研究。与预期相反，我们观察到随着温度降低，阵列电阻急剧下降——类似于超导行为——然后在低温下饱和。施加磁场后，我们最终观察到向高电阻状态的转变。这些观测结果可以在一个考虑热涨落在绝缘相中作用的理论框架内得到理解。基于实验与理论之间的一致性，我们认为我们的约瑟夫森阵列中明显的超导性源于零温绝缘体的熔化。
