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Cri/oFlex®

Measurement Infrastructure

Delft Circuits’ Cri/oFlex® is a modular and scalable I/O system designed for a wide range of quantum applications. The high-density flexible wiring platform offers turnkey, side-loading solutions for flux bias lines and microwave drive lines.

Delft Circuits’ Cri/oFlex® is a modular and scalable I/O system designed for a wide range of quantum applications. The high-density flexible wiring platform utilizes a stripline design based on planar microwave circuitry offering compact formfactor and low thermal load.

Bluefors and Delft Circuits have worked together to smoothly integrate Delft Circuits’ turnkey I/O solution for flux bias and microwave drive lines with Bluefors’ side-loading XLDsl and LDsl Systems. Each side-loader supports up to 256 high-frequency lines, enabling configurations of 64, 128, or 256 channels. This allows up to 1 536 lines to be fitted in an XLDsl System and 512 lines in an LDsl System. The system features SMP connectors at both room temperature and millikelvin stage, coming pre-assembled for easy and reliable installation.

The monolithic design of Cri/oFlex® integrates all signal conditioning components—filters and attenuators—directly on the flex, minimizing connections and preserving signal integrity across thermal stages. With a compact thin-film design of 8 channels per flex, Cri/oFlex® enables stepwise scalability while maintaining a small form factor.

Product Highlights


1.0

Cri/oFlex®

Measurement Infrastructure


Scalable Room Temperature Interface

Cri/oFlex® features a high-density vacuum feedthrough that provides a room-temperature interface for up to 256 lines, ensuring seamless connectivity across all loader configurations—whether fully populated (256 channels), half populated (128 channels), or quarter populated (64 channels). This interface is always included, supporting modular system design and allowing users to scale their setup according to specific quantum application needs.


Cri/oFlex® Platform and Connectors

Cri/oFlex® flex platforms are tailored for specific quantum control needs: Silver (Ag) is used for microwave drive lines, while superconducting Niobium Titanium (NbTi) is used for flux bias lines below the 4K stage. It offers bandwidths up to 12 GHz, with microwave drive lines operating up to 8 GHz and flux bias lines up to 1 GHz. Each flex is equipped with SMP connectors at both the room temperature and mixing chamber stage, ensuring reliable high-frequency connectivity across thermal stages.


Optimized Heat Management and Noise Control

Cri/oFlex® integrates a carefully distributed attenuation profile across thermal stages to optimize both heat load distribution and noise control. For microwave drive lines, attenuation is applied as follows: -10 dB at 4K, -20 dB at 100 mK, and -20 dB at 10 mK, in addition to the cable’s inherent attenuation. Flux bias lines feature -20 dB attenuation at 4K.

Each line type also includes integrated low-pass filters: 8 GHz for microwave drive lines at 100 mK, and 1 GHz for flux bias lines at 50K. To further suppress infrared noise, Cri/oFlex® incorporates infrared filters at 10 mK: -1 dB/GHz for microwave drive lines and -1.5 dB/GHz for flux bias lines.


Efficient Thermalization

The flexible cables are thermalized using precision clamping, ensuring uninterrupted signal integrity. This method provides an elegant and highly efficient solution for managing thermal load.


Technical Specifications


2.0

Cri/oFlex®

Measurement Infrastructure

Parameter
Lines per port256 with configurations of 64, 128, or 256 channels
Total lines in an XLDsl system1 536
Total lines in an LDsl system512
Frequency rangeFlux lines up to 1 GHz

Drive lines up to 8 GHZ
Characteristic impedance50 Ohm
Attenuation (including integrated attenuators)Flux lines up to -30 dB @ 1 GHz

Drive lines -60 dB @ 1 GHz, – 70 dB @ 8 GHz
FiltersFor flux bias lines, a 1 GHz low-pass filter is integrated (@50K) and a -1.5 dB/GHz infrared filter is integrated (@10 mK).

For microwave drive lines, an 8 GHZ low-pass filter is integrated (@100 mK), a -1 dB/GHz infrared filter is integrated (@10 mK).
Insertion loss excluding attenuators (from RT to MXC)-7 dB @ 1 GHz

-14 dB @ 6 GHz
Return lossApprox. 20 dB
Crosstalk range-60 dB @ 1 GHz

-40 dB @ 6 GHz

Related Products


Technical Requirements


3.0

Cri/oFlex®

Measurement Infrastructure

LD400sl

Free side-loading port for installation

XLDsl

Free side-loading port for installation

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