Superconductivity Talks Series

February 10 | 17:00 CET

This is the first recording of the Superconductivity Talks webinar series hosted by the Young Professionals committee of the IEEE Council of Superconductivity. Dr. Halima Ahmad will speak about her research with superconducting quantum circuits.

Since its first discovery in the early ‘60s, the Josephson effect has been a powerful tool to study the fundamental physics occurring in conventional and unconventional superconducting materials and the exotic phenomena arising when coupling superconductors with barriers far from simple insulators or metals [1]. However, Josephson junctions are not just a laboratory platform. The research community has already demonstrated that they can enhance the capabilities of superconducting electronics in real-world applications: from highly sensitive magnetometry to quantum metrology and from quantum detection to quantum computation [2]. In this talk, we will specifically focus on the possibility of building a hybrid classical/quantum superconducting platform for high-performance computing by exploiting unconventional Josephson junctions that use ferromagnetic tunnel barriers (tunnel-SFS JJs) [3-7]. Tunnel SFS JJs have the potential of enlarging the capabilities of current state-of-the-art superconducting electronics [8-12]. The high quality of tunnel JJs adds to the chance to tune the magnetization of the ferromagnetic barrier. We show that this allows setting up a convenient playground for novel control, read-out, and memorization mechanisms. [1] A. Barone and G. Paternò, John Wiley & Sons, Inc. 9780471014690 (1982). [2] F. Tafuri, Vol. 286. Springer Nature, (2019). [3] K. Senapati, et al., Nature Materials, 849 (2011). [4] A. Pal, et al., Nature Communications, 3340 (2014). [5] R. Caruso, et al., Phys. Rev. Lett. 122, 047002 (2019). [6] R. Satariano, et al., Phys. Rev. B 103, 224521 (2020). [7] Ahmad, H. G., et al., arXiv preprint arXiv:2106.15646 (2021). [8] D. Massarotti, et al., Nature Communications, 7376 (2015). [9] H.G. Ahmad, et al., Phys. Rev. Applied 13, 014017 (2020). [10] R. Caruso, et al., Journal of Applied Physics, 123 (2018). [11] Loredana Parlato, et al., Journal of Applied Physics 127, 193901 (2020). [12] H.G. Ahmad et al., submitted paper (2021).

September 21 | 19:00 CET

The long understood benefits of operating fusion devices, such as tokamaks and stellarators, at high fields make superconducting magnets necessary to realize a compact fusion power system. Superconducting stellarators, such as W7-X, have used standard low-temperature superconductor technology (NbTi). ARPA-E has recently funded a 2-year project led by the startup Type One Energy and involving the Fusion Technology Institute at the University of Wisconsin–Madison and the Plasma Science and Fusion Center at MIT, to design and manufacture the first non-planar HTS (REBCO) coil based on the SPARC tokamak’s VIPER cable concept for a high-field stellarator. The design consists of a two-turn non-planar HTS coil supported by a pair of 3D printed stainless steel radial plates. The ultimate goals of the project are to determine if commercial REBCO tapes and additive manufacturing can be used to fabricate high field (>10 T) non-planar coils with tight bending radii (100 mm) and without degradation of the superconducting performance. In this presentation we will report on the fabrication of a two-turn non-planar HTS coil with tight-radius bends that will be supported by a pair of 3D printed stainless steel radial plates. A critical risk that is still to be retired is the accurate 3D bending of a multi-turn coil so that it mates properly with the radial plates, and produces the desired 3D B-field structure. Testing of the completed coil at 77 K will characterize the Ic, the 3D B-field structure, and the quench robustness, and will be compared to detailed electromagnetic, mechanical, and thermal modeling.