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Quantum computers (QCs) are expected to run advanced algorithms to solve currently intractable challenges in chemistry simulations, cryptography, medicine, and finance.[1] The Josephson Junction based qubits that power a quantum computer must reside in a cryogenically cooled chamber at 10 mK. Communications with this chip is currently carried out with a chandelier of rigid cables.[2] A flexible cable containing superconducting interconnect lines could in principle simplify the design of QC interconnects and lead to improvement in qubit density and efficiency. We have previously demonstrated the use of aerosol jet printing (AJP) for the patterning of electrodeposited Cu and Ni [3]. We have also recently reported on the development of a water-in-salt method to electrodeposit superconducting Re on evaporated Au on Si substrates. These Re components have a critical temperature above 4.2 K, which makes the superconductivity easily accessible with liquid He cooling[4]. We report for the first time the metallization of flexible Kapton substrates with printed Au and Ag nanoparticle inks by aerosol jet printing as the seed for superconductor electrodeposition. Electrodeposition of Re onto the printed structures was performed using the water-in-salt method. ASTM D3359 tests demonstrated that Au has superior adhesion to Kapton, while the Ag seed does not survive rhenium deposition, potentially due to the high internal stress of Re. Further, improved adhesion was demonstrated when Kapton substrates were roughened with 1200 grit sandpaper. Electrodeposited Re on AJP Au seed layer on flexible Kapton substrates, as shown in Figure 1, demonstrated a superconducting transition temperature of 6K. In addition, electrodeposited Re on Au survived 200 cycles of flexure testing under >30 MPa load and 1.2% strain. These efforts demonstrate the proof-of-principle for patterning of superconducting interconnects for the further development of QCs. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2022-11522 A References [1] F. Bova, A. Goldfarb, and R.G. Melko “Commercial Applications of Quantum Computing.” EPJ Quantum Tech. (2021) 8:2. [2] S. Krinner, S. Storz, P. Kurpiers, P. Magnard, J. Heinsoo, R. Keller, J. Lütolf, C. Eichler & A. Wallraff. “Engineering cryogenic setups for 100-qubit scale superconducting circuit systems.” EPJ Quantum Tech. (2019) 6:2. [3] L. K. Tsui, S. C. Kayser, S. A. Strong, and J. M. Lavin, “High Resolution Aerosol Jet Printed Components with Electrodeposition-Enhanced Conductance.” ECS J. Solid State Sci. Tech. (2021). 10, 047001. [4] W. D. Sides, E. Hassani, D. P. Pappas, Y. Hu, T. S. Oh, Q. Huang “Grain growth and superconductivity of rhenium electrodeposited from water-in-salt electrolytes.” J. App. Phys. (2020). 127, 085301. Figure 1. (a) Photograph of a well adhered Re on Au sample. (b) Superconducting transition data for Re on printed Au on Kapton. Figure 1

Superconductors with enhanced superconducting critical temperatures (Tc) above the boiling point of liquid helium (4.2 K) are of interest for interconnections in superconducting quantum computing systems to avoid ohmic heating[1]. Crystalline Re in bulk is a type-I superconductor with a Tc of about 1.7K[2]. An elevated Tc up to about 6K in electrodeposited amorphous Re has been reported[3]. In addition, various elevation in Tc has also been reported for Re film under shear strain[4] or doped with foreign elements such as Tungsten (W), Osmium (Os), and Carbon (C)[5, 6]. This work aims to test a hypothesis that the Tc of electrodeposited Re films can be tuned using compressive and tensile strains on the Re films generated with thermal expansions difference. Figure 1 shows a diagram of the strains on Re film sandwiched between metals with different coefficients of thermal expansions (CTEs) when the temperature is lowered. For example, Cu has a higher CTE than Re and Cr has a slightly lower CTE than Re. Such sandwich structures are prepared at room temperature using electrochemical deposition. The DC resistance measurements at cryogenic temperatures confirmed that the superconducting transition for the Re films sandwiched between Cu occurs at a lower temperature than the Re film alone. On the other hand, when Cr is used, the sandwiched Re structure shows a slightly enhanced superconducting critical temperature. The effect of thermal annealing i.e., the recrystallization of electrodeposited Re films at an elevated temperature, and electrochemical behavior of Re, Cr, and Cu electrodeposition will be discussed in the talk. References Radenbaugh, R., Refrigeration for superconductors. Proceedings of the IEEE, 2004. 92(10): p. 1719-1734. Hulm, J.K., Superconductivity of Pure Metallic Rhenium. Physical Review, 1954. 94(5): p. 1390-1391. Pappas, D.P., et al., Enhanced superconducting transition temperature in electroplated rhenium. Applied Physics Letters, 2018. 112(18): p. 182601. Mito, M., et al., Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain. Scientific Reports, 2016. 6(1): p. 36337. Chu, C.W., W.L. McMillan, and H.L. Luo, Superconductivity of Re-Os, Re-Ru, Ru-Os, and Re-W hcp Alloy Systems and Slightly Doped Re. Physical Review B, 1971. 3(11): p. 3757-3762. Zhu, Q., et al., Anisotropic lattice expansion and enhancement of superconductivity induced by interstitial carbon doping in Rhenium. Journal of Alloys and Compounds, 2021. 878: p. 160290. Figure 1