Hardware Guide

The Pursuit of High Density and System Integration

As quantum processors scale from tens of qubits to hundreds or even thousands, the number of required signal lines grows explosively. However, space inside a dilution refrigerator, especially at the coldest mK stage, is extremely precious. The volume, thermal load, and assembly complexity of traditional coaxial cables make it difficult to meet this demand, thus driving the development of new technologies.

Flexible ribbon cable technology (such as Delft Circuits' Cri/oFlex® and Maybell's Flexlines) has emerged to address this. These cables can accommodate multiple channels in a very small cross-sectional area and have excellent flexibility, greatly increasing wiring density and ease of installation. At the same time, high-density connector technology (like Rosenberger's multiport systems and Ardent Concepts' board-level connectors) allows for more connection points in a smaller area and simplifies the assembly and maintenance process through single-plug operations. Furthermore, directly integrating passive components like filters and attenuators onto flexible cables not only saves valuable cryogenic space but also reduces the number of contact points, improving the overall reliability of the system.

Balancing Material Engineering Properties

Another core trend is balancing multiple and conflicting physical requirements through materials science. Cryogenic cables and connectors must operate reliably across an extreme temperature range, from room temperature to near absolute zero. This means the materials must simultaneously meet the following demanding conditions:

The core conflict lies in the need for materials to have both excellent "electrical conductivity" for low-loss RF signal transmission and extremely poor "thermal conductivity" to insulate against heat. To achieve this delicate balance, suppliers and research institutions are constantly exploring and optimizing material systems. For example, using low-thermal-conductivity alloys like stainless steel or cupronickel as the conductor substrate, supplemented with a thin layer of a good conductor (like silver) to improve RF performance. At the coldest stages, the unique properties of superconducting materials like Niobium-Titanium (NbTi) are utilized to achieve both zero resistance and extremely low thermal conductivity. Additionally, materials must possess good "mechanical properties" (such as flexibility at low temperatures and resistance to thermal cycling fatigue) and "electromagnetic properties" (such as being non-magnetic). Finding new materials or composite structures that excel in all these areas remains a key focus of ongoing R&D in the field.

Component Category	Supplier	Country/Region	Key Products/Services	Key Features/Technology
Cryogenic Wiring & Connectors	Delft Circuits	Netherlands	Cri/oFlex® flexible cables (Ag/NbTi), cryogenic connectors, hermetic feedthroughs, T2B interface, high-density Feedthroughs (up to 256 ch)	High density, low thermal conductivity, integrable components, superconducting options
	Rosenberger	Germany	Cryogenic coaxial cables (SS, CuNi, NbTi), non-magnetic RF connectors (SMA, SMP), high-density connectors, flexible cables, ribbon cables	Broad product line, strong customization capability, high-frequency performance, non-magnetic options, wide frequency range (up to 110 GHz), high-density solutions
	CryoCoax (Intelliconnect)	UK	Cryogenic RF interconnect components and subsystems, high-density connectors	Specializes in RF solutions for cryogenic applications
	Amphenol Aerospace	USA	Cryo-Seal™ hermetic connectors (based on 38999 mil-spec)	Guaranteed performance at very low temperatures (-195°C), high hermeticity, glass-to-metal seals
	Martec	UK	Custom cryogenic hermetic connectors/feedthroughs	Vacuum-friendly, low-outgassing materials
	Quantum Microwave	USA	Non-magnetic cryogenic connectors (SMA, SMP, SMPS, etc.)	Provides various microwave components specifically for quantum labs
	Maybell Quantum	USA	Flexlines (flexible ribbon cables), cryogenic platforms	Focuses on scalable cryogenic hardware solutions
	Ardent Concepts	USA	High-density connections for QPU packaging (board-to-board or cable-to-board)	High-density board-level connectors
Auxiliary Systems	Leybold, Edwards, Pfeiffer	(Multinational)	Various vacuum pumps (rotary, dry, turbo, ion, etc.)	Established vacuum technology suppliers
	SAES Getters	Italy	Non-Evaporable Getter (NEG) pumps	High pumping speed for H₂, no vibration or magnetic field interference
	Amuneal, Magnetic Shields Ltd.	USA, UK	Magnetic shielding materials and systems (μ-metal)	High-permeability materials, custom cryogenic active and passive shielding
	Lake Shore Cryotronics	USA	Cryogenic temperature/magnetic field sensors, measurement instruments, probe stations	Experts in the field of cryogenic measurement

Startup & Product Example	Product Image (Images from official websites)
Delft Circuits
CryoCoax High Density Connectors
Maybell Wiring Fridge solutions
Quantum Microwave Magnetic-shielding Cryogenic Breadboard
Ardent Concepts Plate-to-plate connection

Originally written in Chinese by the author, these articles are translated into English to invite cross-language resonance.