Towards Efficient Superconducting Devices and Circuits Through Ubiquitous Superconducting Diode Effect in Superconductor Thin Films

Recent work on thin film hybrid of superconductor/ferromagnetic semiconductor (SC/FM) led to the observation of nonreciprocity of critical supercurrent, called superconducting (SC) diode effect. Accomplishing unequal supercurrents in SC films in the forward and backward directions enables unprecedented functionalities. We demonstrated strong SC diode effect in conventional SC thin films, such as Nb and V, employing external magnetic fields as small as 1 Oe while in the case of the SC layer interfaced with an FM of EuS, even in the absence of any applied field [1]. SC diode efficiencies reached giant values ~70%. We identified that the critical supercurrent nonreciprocity in SC/FM bilayer (or just as SC) thin films was accomplished with asymmetrical vortex edge/surface barriers and the universal Meissner screening current. This led us to develop superconducting electronic devices, essential for energy-efficient quantum and classical high-end computing applications. One of the critical long-standing requirements is the need for dc bias current delivery for superconducting energy-efficient rapid single flux quantum (ERSFQ) circuits. By SC diode rectifiers one can address this issue and solve the rise of total dc bias current with the number of cells. This enables the ERSFQ scalability to larger circuit complexities by demonstrating non-reciprocal SC circuit elements as SC diode bridge rectifiers, isolators, nonvolatile memory elements, etc. operating at few Kelvin, and thus fulfill many critical needs. We present our recent superconducting rectifier [2] and nonvolatile memory results along these lines showing a pathway with our highly scalable thin film platform. There is a high potential for significant energy reduction and would also lower the decohering thermal and electromagnetic noise in quantum computing.

[1] Hou et al. Phys. Rev. Lett. 131, 027001 (2023)

[2] Ingla-Aynes et al. arXiv:2406.12012 (2024)