https://research-explorer.ista.ac.at 2000-01-01T00:00+00:00 1 weekly https://research-explorer.ista.ac.at/record/18057 Mukhopadhyay, Soham Lancheros Naranjo, Diego A Senior, Jorden L Higginbotham, Andrew P 2024 We report relaxation oscillations in a one-dimensional array of Josephson junctions. The oscillations are circuit-dual to those ordinarily observed in single junctions. The dual circuit quantitatively accounts for temporal dynamics of the array, including the dependence on biasing conditions. Injection locking the oscillations results in well-developed current plateaux. A thermal model explains the relaxation step of the oscillations. https://research-explorer.ista.ac.at/record/18057 eng info:eu-repo/semantics/altIdentifier/doi/10.48550/arXiv.2408.07829 info:eu-repo/semantics/altIdentifier/arxiv/2408.07829 info:eu-repo/grantAgreement/EC/H2020/754411 info:eu-repo/grantAgreement/FWF/P33692 info:eu-repo/semantics/openAccess Mukhopadhyay S, Lancheros Naranjo DA, Senior JL, Higginbotham AP. Dual relaxation oscillations in a Josephson junction array. <i>arXiv</i>. doi:<a href="https://doi.org/10.48550/arXiv.2408.07829">10.48550/arXiv.2408.07829</a> Dual relaxation oscillations in a Josephson junction array info:eu-repo/semantics/preprint doc-type:preprint text http://purl.org/coar/resource_type/c_816b https://research-explorer.ista.ac.at/record/14032 Mukhopadhyay, Soham Senior, Jorden L Saez Mollejo, Jaime Puglia, Denise Zemlicka, Martin Fink, Johannes M Higginbotham, Andrew P 2023 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. https://research-explorer.ista.ac.at/record/14032 https://research-explorer.ista.ac.at/download/14032/14899 eng Springer Nature info:eu-repo/semantics/altIdentifier/doi/10.1038/s41567-023-02161-w info:eu-repo/semantics/altIdentifier/issn/1745-2473 info:eu-repo/semantics/altIdentifier/issn/1745-2481 info:eu-repo/semantics/altIdentifier/wos/001054563800006 info:eu-repo/grantAgreement/FWF/P33692 info:eu-repo/grantAgreement/EC/H2020/754411 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Mukhopadhyay S, Senior JL, Saez Mollejo J, et al. Superconductivity from a melted insulator in Josephson junction arrays. <i>Nature Physics</i>. 2023;19:1630-1635. doi:<a href="https://doi.org/10.1038/s41567-023-02161-w">10.1038/s41567-023-02161-w</a> General Physics and Astronomy ddc:530 Superconductivity from a melted insulator in Josephson junction arrays info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://research-explorer.ista.ac.at/record/9402 Schmid, Laura Chatterjee, Krishnendu Hilbe, Christian Nowak, Martin A. 2021 Direct and indirect reciprocity are key mechanisms for the evolution of cooperation. Direct reciprocity means that individuals use their own experience to decide whether to cooperate with another person. Indirect reciprocity means that they also consider the experiences of others. Although these two mechanisms are intertwined, they are typically studied in isolation. Here, we introduce a mathematical framework that allows us to explore both kinds of reciprocity simultaneously. We show that the well-known ‘generous tit-for-tat’ strategy of direct reciprocity has a natural analogue in indirect reciprocity, which we call ‘generous scoring’. Using an equilibrium analysis, we characterize under which conditions either of the two strategies can maintain cooperation. With simulations, we additionally explore which kind of reciprocity evolves when members of a population engage in social learning to adapt to their environment. Our results draw unexpected connections between direct and indirect reciprocity while highlighting important differences regarding their evolvability. https://research-explorer.ista.ac.at/record/9402 https://research-explorer.ista.ac.at/download/9402/14496 eng Springer Nature info:eu-repo/semantics/altIdentifier/doi/10.1038/s41562-021-01114-8 info:eu-repo/semantics/altIdentifier/issn/2397-3374 info:eu-repo/semantics/altIdentifier/wos/000650304000002 info:eu-repo/semantics/altIdentifier/pmid/33986519 info:eu-repo/grantAgreement/EC/H2020/863818 info:eu-repo/grantAgreement/EC/FP7/279307 info:eu-repo/semantics/openAccess Schmid L, Chatterjee K, Hilbe C, Nowak MA. A unified framework of direct and indirect reciprocity. <i>Nature Human Behaviour</i>. 2021;5(10):1292–1302. doi:<a href="https://doi.org/10.1038/s41562-021-01114-8">10.1038/s41562-021-01114-8</a> ddc:000 A unified framework of direct and indirect reciprocity info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501