Delft Circuits
Flux Bias Lines
Flux Bias Lines are specialized superconducting cabling assemblies designed to deliver baseband bias signals to superconducting qubits and tunable couplers within cryogenic quantum systems. Constructed on Delft Circuits’s flexible silver and NbTi stripline platform, Flux Lines provide ultra-low resistance, integrated filtering, and minimal thermal load between room-temperature control electronics and millikelvin stages, enabling precise flux tuning in scalable quantum processors.
Designed for reliability and integration with modern dilution refrigerators, Flux Bias Lines support low-frequency control signals with thermally efficient performance across temperature gradients from room temperature down to 10 mK.
Key Applications
- Bias control for tunable qubits and coupler
- Bias voltage for semiconductor spin qubit
- Bias voltage and current modulation for single photon detector
Key Features
- Low resistance: minimal contact resistance (~10 mΩ)
- Low crosstalk: equal level far end crosstalk of -80 dB at 200 MHz
- Low loss: 1 dB/m for silver flex and 0.5 dB/m for NbTi flex at 1 GHz in superconducting stage at 4K
- Cryogenic performance: thermalize time constant of 0.28 ms, twice as fast as coaxial setup
- Specialized package: comes with integrated filters design for flux control
- Flexibility: Cri/oFlex design with high flexibility
- Scalability: comes in compact kit KF25 with 8 channels and up to 256 channels in 108 mm port assembly
Technical Highlights
- Flex material strip line design with high flexibility and high-density channels
- Superconducting NbTi platform for low loss transmission
- Filtering integrated into the flex to reduce mechanical strain
- Thermalization by clamping with increases surface area
Configuration options
- Integrated filtering elements:Attenuators, low pass filters, infrared filters
- Comparable with a wide range ofcryostats, including Bluefors, Maybell, FormFactor, Oxford Instruments, LeidenCryogenics and Kiutra
- Comes in many packages forscalability:
- KF25: 8 to 16 channels with SMAand SMP connectors
- KF40: 8 to 32 channels with SMA and SMP connectors, 32 to 64 channels with HD SMP and HD SMPM port
- ISO-K63: 32 to 96 channels withHD SMP and HD SMPM port
- Ø 108 mm port: 32 to 256 channels with HD SMP and HD SMPM port
Discover Cri/oFlex lines yourself
Ready to experience the performance of Flux Bias Lines? Request a live demonstration, download detailed datasheets, or contact our team to discuss a customized configuration for your system. Delft Circuits is here to help you achieve exceptional results with precision cryogenic connectivity.
