Low-Temperature Superconducting Coaxial Cables

Low-Temperature Superconducting Coaxial Cables (LTS Coaxial Cables) are indispensable “neural fibers” in ultra-low-temperature physics experiments and cutting-edge technologies such as quantum computing.

To better understand these cables, we can examine them from three perspectives: their structure, their working principles, and the fundamental challenges they are designed to solve.

1. Core Structure: Why Is It Called “Coaxial”?

Structurally, low-temperature superconducting coaxial cables adopt a coaxial configuration similar to conventional household coaxial TV cables. However, the materials and operating conditions are fundamentally different.

Inner and outer conductors: These are typically made of low-temperature superconducting materials such as NbTi (Niobium-Titanium).

Insulation layer (dielectric): Located between the inner and outer conductors, the dielectric is usually a material with extremely low dielectric loss, such as PTFE (Teflon).

Operating environment: The cable must operate at extremely low temperatures—usually below 4.2 K (the temperature of liquid helium). Under these conditions, the superconducting material enters a zero-resistance state.

This coaxial structure ensures stable transmission of high-frequency signals with minimal loss under cryogenic conditions.

2. Why Use Superconducting Materials for Cables?

In precision experiments such as quantum chip control, microwave signals must be transmitted from a room-temperature environment down to an ultra-low-temperature stage (for example, 20 mK). If conventional copper cables are used, two critical problems arise.

Signal attenuation (signal loss): Ordinary metals have electrical resistance. During high-frequency signal transmission, energy is converted into heat, causing signal amplitude to decay and potentially leading to signal distortion or loss.

Thermal conduction (heat leakage challenge): Copper is not only a good electrical conductor but also an excellent thermal conductor. Heat from the room-temperature side can easily flow along the cable into the cryogenic region, placing a heavy thermal load on the refrigeration system and potentially causing system instability.

The “magic” of low-temperature superconducting cables lies in their zero electrical resistance and low thermal conductivity, allowing microwave signals to be transmitted with almost no loss while effectively protecting the ultra-low-temperature environment.

3. Application Scenarios

Quantum Computing: These cables deliver microwave control and readout signals precisely to superconducting qubits, minimizing decoherence caused by thermal noise.

High Magnetic Field Physics: In particle accelerators and MRI systems, superconducting coaxial cables ensure reliable high-frequency signal transmission under strong magnetic fields.

Space Exploration: In satellites and infrared detection systems requiring cryogenic cooling, these cables help maintain extremely high sensitivity while reducing thermal load.

4. Low-Temperature Superconductors (LTS) vs. High-Temperature Superconductors (HTS)

Low-Temperature Superconducting Coaxial Cable (LTS): Materials include NbTi and Nb3Sn, operating below 10 K using liquid helium, primarily for signal transmission and precision measurement.

High-Temperature Superconducting Power Cable (HTS): Materials include YBCO and BSCCO, operating at 65–77 K using liquid nitrogen, primarily for high-current power transmission.

Conclusion

Low-temperature superconducting coaxial cables can be regarded as zero-loss micro-scale information highways. They ensure near-lossless microwave signal transmission while suppressing heat leakage in ultra-low-temperature systems.

With long-term experience in high-frequency and precision cable technologies, Hotten continues to refine conductor materials, dielectric structures, and overall cable stability, providing reliable low-temperature and high-frequency signal transmission solutions for advanced research and high-end applications.