Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Smart Systems Integration Conference and Exhibition (SSI)

Roll-to-roll fabrication of superconducting flexible shielded high-density interconnects for scalable quantum computing

Elias Meltzer, Martijn H. Goedbloed, Jargal Hepp, Carla Morán Guizán, Manish Pandey, Johannes Weber, Daniela Zahn, Maryam Faghih, Rui N. Pereira, Christoph Kutter

Published Apr 8, 2025• 0 citations
Publisher

Abstract

A high density wiring solution is indispensable for the scaling up of superconducting qubit-based quantum computers. With increasing numbers of qubits, implementing conventional coax cables with SMA connectors inside a cryostat is no longer feasible. Here we propose the roll-to-roll manufacturing route for a thin and flexible high-density interconnect solution based on niobium and polyimide together with a PCB-direct connector. The feasibility of this process is demonstrated by fabrication of 150 mm long flexible cables, featuring 16 shielded transmission lines which become superconducting below 6 K.

DOI
10.1109/ssi65953.2025.11517923

Related papers

Flexible superconducting Nb transmission lines on thin film polyimide for quantum computing applications

David B. Tuckerman, Michael C. Hamilton, D. J. Reilly +5 more

We describe progress and initial results achieved towards the goal of developing integrated multi-conductor arrays of shielded controlled-impedance flexible superconducting transmission lines with ultra-miniature cross sections and wide bandwidths (dc to >10 GHz) over meter-scale lengths. Intended primarily for use in future scaled-up quantum computing systems, such flexible thin-film niobium/polyimide ribbon cables could provide a physically compact and ultra-low thermal conductance alternative to the rapidly increasing number of discrete coaxial cables that are currently used by quantum computing experimentalists to transmit signals between the several low-temperature stages (from ∼4 K down to ∼20 mK) of a dilution refrigerator. We have concluded that these structures are technically feasible to fabricate, and so far they have exhibited acceptable thermo-mechanical reliability. S -parameter results are presented for individual 2-metal layer Nb microstrip structures having 50 Ω characteristic impedance; lengths ranging from 50 to 550 mm were successfully fabricated. Solderable pads at the end terminations allowed testing using conventional rf connectors. Weakly coupled open-circuit microstrip resonators provided a sensitive measure of the overall transmission line loss as a function of frequency, temperature, and power. Two common microelectronic-grade polyimide dielectrics, one conventional and the other photo-definable (PI-2611 and HD-4100, respectively) were compared. Our most striking result, not previously reported to our knowledge, was that the dielectric loss tangents of both polyimides, over frequencies from 1 to 20 GHz, are remarkably low at deep cryogenic temperatures, typically 100 × smaller than corresponding room temperature values. This enables fairly long-distance (meter-scale) transmission of microwave signals without excessive attenuation, and also permits usefully high rf power levels to be transmitted without creating excessive dielectric heating. We observed loss tangents as low as 2.2 × 10 −5 at 20 mK, although losses increased somewhat at very low rf power levels, similar to the well-known behavior of amorphous inorganic dielectrics such as SiO 2 . Our fabrication techniques could be extended to more complex structures such as multiconductor cables, embedded microstrip, 3-metal layer stripline or rectangular coax, and integrated attenuators and thermalization structures.

arXiv:1606.04557•Superconductor Science and Technology•Jul 11, 2016•73 citations

Superconducting Flexible Shielded Interconnects For Scalable Quantum Computing

Martijn H. Goedbloed, Elias Meltzer, Jargal Hepp +7 more

The development of large-scale quantum processors requires an increasing number of transmission lines for efficient signal processing. However, the complexity of these systems poses challenges that current commercially available cryogenic cables cannot effectively address. To meet future requirements, a flexible and scalable approach for managing the growing number of connections while ensuring optimal performance is essential.

Smart Systems Integration Conference and Exhibition (SSI)•Apr 8, 2025•0 citations

Improved Flexible Coaxial Ribbon Cable for High-Density Superconducting Arrays

Jennifer Pearl Smith, Benjamin A. Mazin, Alírio Boaventura +2 more

Superconducting arrays often require specialized, high-density cryogenic cabling capable of transporting electrical signals across temperature stages with minimal loss, crosstalk, and thermal conductivity. We report improvements to the design and fabrication of previously published superconducting 53 wt% Niobium (Nb)-47 wt% titanium (Ti) flexible coaxial ribbon cables. We used 3-D electromagnetic simulations to inform design changes to improve the characteristic impedance of the cable and the connector transition. We increased the center conductor diameter from 0.003 to 0.005 in, which lowered the cable characteristic impedance from$\sim$60 to$\sim$53$\Omega$. This change had a negligible impact on the computed heat load, which we estimate to be 5 nW per trace from 1 K to 100 mK with a 1-ft cable. This is approximately half the heat load calculated for the smallest commercially available superconducting coax. We also modified the transition board to include a capacitive coupling between the upper ground plane and signal traces that mitigates the inductive transition. We tested these changes in a 5-trace, 1-ft long cable at 4 K and found the microwave transmission improved from 6 to 1.5 dB of attenuation at 8 GHz. This loss is comparable to commercial superconducting coax and 3× lower than commercial NbTi-on-polyimide flex cables at 8 GHz. The nearest-neighbor forward crosstalk remained −50 dB. We compare key performance metrics with commercially available superconducting coax and NbTi-on-polyimide flex cables and we share initial progress on commercialization of this technology by Maybell Quantum Industries.

arXiv:2306.13574•IEEE Transactions on Applied Superconductivity•Jan 5, 2024•7 citations

Flexible Coaxial Ribbon Cable for High-Density Superconducting Microwave Device Arrays

Jennifer Pearl Smith, Benjamin A. Mazin, Alex B. Walter +7 more

Superconducting electronics often require high-density microwave interconnects capable of transporting signals between temperature stages with minimal loss, cross talk, and heat conduction. We report the design and fabrication of superconducting 53 wt% Nb-47 wt% Ti (Nb47Ti) FLexible coAXial ribbon cables (FLAX). The ten traces each consist of a ø0.076 mm NbTi inner conductor insulated with PFA (ø0.28 mm) and sheathed in a shared 0.025 mm thick Nb47Ti outer conductor. The cable is terminated with G3PO coaxial push-on connectors via stainless steel capillary tubing (ø1.6 mm, 0.13 mm thick) soldered to a coplanar wave guide transition board. The 30 cm long cable has 1 dB of loss at 8 GHz with -60 dB nearest neighbor forward cross talk. The loss is 0.5 dB more than commercially available superconducting coax likely due to impedance mismatches caused by manufacturing imperfections in the cable. The reported cross talk is 30 dB lower than previously developed laminated NbTi-on-Kapton microstrip cables. We estimate the heat load from 1 K to 90 mK to be 20 nW per trace, approximately half the computed load from the smallest commercially available superconducting coax from CryoCoax.

arXiv:2007.06496•IEEE Transactions on Applied Superconductivity•Jul 10, 2020•21 citations

High-Density Qubit Wiring: Pin-Chip Bonding for Fully Vertical Interconnects

M. Mariantoni, A.V. Bardysheva

Large-scale quantum computers with more than $10^5$ qubits will likely be built within the next decade. Trapped ions, semiconductor devices, and superconducting qubits among other physical implementations are still confined in the realm of medium-scale quantum integration ($\sim 100$ qubits); however, they show promise toward large-scale quantum integration. Building large-scale quantum processing units will require truly scalable control and measurement classical coprocessors as well as suitable wiring methods. In this blue paper, we introduce a fully vertical interconnect that will make it possible to address $\sim 10^5$ superconducting qubits fabricated on a single silicon or sapphire chip: Pin-chip bonding. This method permits signal transmission from DC to $\sim 10$ GHz, both at room temperature and at cryogenic temperatures down to $\sim 10$ mK. At temperatures below $\sim 1$ K, the on-chip wiring contact resistance is close to zero and all signal lines are in the superconducting state. High-density wiring is achieved by means of a fully vertical interconnect that interfaces the qubit array with a network of rectangular coaxial ribbon cables. Pin-chip bonding is fully compatible with classical high-density test board applications as well as with other qubit implementations.

arXiv:1810.08580•Oct 19, 2018•3 citations

Thin-Film Nb/Polyimide Superconducting Stripline Flexible Cables

Vaibhav Gupta, Bhargav Yelamanchili, Simin Zou +4 more

We present recent work on design, fabrication, and characterization of thin-film, flexible superconducting stripline cables. Fabrication details, dc, and microwave performance (up to 14 GHz) of cables with Al/Nb/Al conductors and polyimide (PI) dielectric are discussed. Thin Al was used as a barrier layer between Nb and polyimide to protect the Nb superconductivity during subsequent PI curing steps, which were performed at a reduced temperature. The dc performance, including critical transition temperature and critical current, of the stripline transmission lines is presented. We observed Tcvalues of ~8.8 and ~8.6 K for signal traces and ground planes, respectively. Microwave characterization, including cross-talk, was performed on stripline transmission lines and resonators. We observed reasonable impedance match (S11better than -15 dB), low insertion loss (S21better than 0.04 dB/cm) and cross-talk below -60 dB for stripline transmission lines measured up to 10 GHz at 4.2 K. Furthermore, similarly fabricated stripline resonators exhibited quality factors ~7 000 at 10 GHz and 1.2 K for stripline resonators. The results of these experiments provide insight into material stack-ups for robust, multi-layer superconducting flexible cables that can find use in future cryogenic electronics systems.

IEEE Transactions on Applied Superconductivity•Mar 18, 2019•20 citations
A high density wiring solution is indispensable for the scaling up of superconducting qubit-based quantum computers. With increasing numbers of qubits, implementing conventional coax cables with SMA connectors inside a cryostat is no longer feasible. Here we propose the roll-to-roll manufacturing route for a thin and flexible high-density interconnect solution based on niobium and polyimide together with a PCB-direct connector. The feasibility of this process is demonstrated by fabrication of 150 mm long flexible cables, featuring 16 shielded transmission lines which become superconducting below 6 K.
We describe progress and initial results achieved towards the goal of developing integrated multi-conductor arrays of shielded controlled-impedance flexible superconducting transmission lines with ultra-miniature cross sections and wide bandwidths (dc to >10 GHz) over meter-scale lengths. Intended primarily for use in future scaled-up quantum computing systems, such flexible thin-film niobium/polyimide ribbon cables could provide a physically compact and ultra-low thermal conductance alternative to the rapidly increasing number of discrete coaxial cables that are currently used by quantum computing experimentalists to transmit signals between the several low-temperature stages (from ∼4 K down to ∼20 mK) of a dilution refrigerator. We have concluded that these structures are technically feasible to fabricate, and so far they have exhibited acceptable thermo-mechanical reliability. S -parameter results are presented for individual 2-metal layer Nb microstrip structures having 50 Ω characteristic impedance; lengths ranging from 50 to 550 mm were successfully fabricated. Solderable pads at the end terminations allowed testing using conventional rf connectors. Weakly coupled open-circuit microstrip resonators provided a sensitive measure of the overall transmission line loss as a function of frequency, temperature, and power. Two common microelectronic-grade polyimide dielectrics, one conventional and the other photo-definable (PI-2611 and HD-4100, respectively) were compared. Our most striking result, not previously reported to our knowledge, was that the dielectric loss tangents of both polyimides, over frequencies from 1 to 20 GHz, are remarkably low at deep cryogenic temperatures, typically 100 × smaller than corresponding room temperature values. This enables fairly long-distance (meter-scale) transmission of microwave signals without excessive attenuation, and also permits usefully high rf power levels to be transmitted without creating excessive dielectric heating. We observed loss tangents as low as 2.2 × 10 −5 at 20 mK, although losses increased somewhat at very low rf power levels, similar to the well-known behavior of amorphous inorganic dielectrics such as SiO 2 . Our fabrication techniques could be extended to more complex structures such as multiconductor cables, embedded microstrip, 3-metal layer stripline or rectangular coax, and integrated attenuators and thermalization structures.
Superconducting arrays often require specialized, high-density cryogenic cabling capable of transporting electrical signals across temperature stages with minimal loss, crosstalk, and thermal conductivity. We report improvements to the design and fabrication of previously published superconducting 53 wt% Niobium (Nb)-47 wt% titanium (Ti) flexible coaxial ribbon cables. We used 3-D electromagnetic simulations to inform design changes to improve the characteristic impedance of the cable and the connector transition. We increased the center conductor diameter from 0.003 to 0.005 in, which lowered the cable characteristic impedance from$\sim60to60 to60to\sim535353\Omega$. This change had a negligible impact on the computed heat load, which we estimate to be 5 nW per trace from 1 K to 100 mK with a 1-ft cable. This is approximately half the heat load calculated for the smallest commercially available superconducting coax. We also modified the transition board to include a capacitive coupling between the upper ground plane and signal traces that mitigates the inductive transition. We tested these changes in a 5-trace, 1-ft long cable at 4 K and found the microwave transmission improved from 6 to 1.5 dB of attenuation at 8 GHz. This loss is comparable to commercial superconducting coax and 3× lower than commercial NbTi-on-polyimide flex cables at 8 GHz. The nearest-neighbor forward crosstalk remained −50 dB. We compare key performance metrics with commercially available superconducting coax and NbTi-on-polyimide flex cables and we share initial progress on commercialization of this technology by Maybell Quantum Industries.
Superconducting electronics often require high-density microwave interconnects capable of transporting signals between temperature stages with minimal loss, cross talk, and heat conduction. We report the design and fabrication of superconducting 53 wt% Nb-47 wt% Ti (Nb47Ti) FLexible coAXial ribbon cables (FLAX). The ten traces each consist of a ø0.076 mm NbTi inner conductor insulated with PFA (ø0.28 mm) and sheathed in a shared 0.025 mm thick Nb47Ti outer conductor. The cable is terminated with G3PO coaxial push-on connectors via stainless steel capillary tubing (ø1.6 mm, 0.13 mm thick) soldered to a coplanar wave guide transition board. The 30 cm long cable has 1 dB of loss at 8 GHz with -60 dB nearest neighbor forward cross talk. The loss is 0.5 dB more than commercially available superconducting coax likely due to impedance mismatches caused by manufacturing imperfections in the cable. The reported cross talk is 30 dB lower than previously developed laminated NbTi-on-Kapton microstrip cables. We estimate the heat load from 1 K to 90 mK to be 20 nW per trace, approximately half the computed load from the smallest commercially available superconducting coax from CryoCoax.
Large-scale quantum computers with more than 10510^5105 qubits will likely be built within the next decade. Trapped ions, semiconductor devices, and superconducting qubits among other physical implementations are still confined in the realm of medium-scale quantum integration (∼100\sim 100∼100 qubits); however, they show promise toward large-scale quantum integration. Building large-scale quantum processing units will require truly scalable control and measurement classical coprocessors as well as suitable wiring methods. In this blue paper, we introduce a fully vertical interconnect that will make it possible to address ∼105\sim 10^5∼105 superconducting qubits fabricated on a single silicon or sapphire chip: Pin-chip bonding. This method permits signal transmission from DC to ∼10\sim 10∼10 GHz, both at room temperature and at cryogenic temperatures down to ∼10\sim 10∼10 mK. At temperatures below ∼1\sim 1∼1 K, the on-chip wiring contact resistance is close to zero and all signal lines are in the superconducting state. High-density wiring is achieved by means of a fully vertical interconnect that interfaces the qubit array with a network of rectangular coaxial ribbon cables. Pin-chip bonding is fully compatible with classical high-density test board applications as well as with other qubit implementations.
We present recent work on design, fabrication, and characterization of thin-film, flexible superconducting stripline cables. Fabrication details, dc, and microwave performance (up to 14 GHz) of cables with Al/Nb/Al conductors and polyimide (PI) dielectric are discussed. Thin Al was used as a barrier layer between Nb and polyimide to protect the Nb superconductivity during subsequent PI curing steps, which were performed at a reduced temperature. The dc performance, including critical transition temperature and critical current, of the stripline transmission lines is presented. We observed Tcvalues of ~8.8 and ~8.6 K for signal traces and ground planes, respectively. Microwave characterization, including cross-talk, was performed on stripline transmission lines and resonators. We observed reasonable impedance match (S11better than -15 dB), low insertion loss (S21better than 0.04 dB/cm) and cross-talk below -60 dB for stripline transmission lines measured up to 10 GHz at 4.2 K. Furthermore, similarly fabricated stripline resonators exhibited quality factors ~7 000 at 10 GHz and 1.2 K for stripline resonators. The results of these experiments provide insight into material stack-ups for robust, multi-layer superconducting flexible cables that can find use in future cryogenic electronics systems.