The Need

Advanced quantum technologies, cryogenic sensors, and space instrumentation increasingly require reliable, compact cooling below 1 K. Today’s sub-Kelvin refrigeration relies heavily on dilution refrigerators and gas-gap thermal switches that are complex, slow, mechanically fragile, and dependent on scarce helium-3. These limitations constrain scalability, increase cost, and reduce system reliability. There is a clear unmet need for a high-performance, solid-state, helium-free thermal switching and refrigeration approach that enables faster cycling, higher cooling power, and simpler system integration.

The Technology

OSU engineers have developed magnetic-field-activated, all-solid-state thermal switches based on topological quantum materials, integrated into adiabatic demagnetization refrigeration (ADR) stages. Two complementary switches are used: one whose thermal conductivity increases with magnetic field and another whose conductivity decreases with field. Critically, both switches are actuated by the same magnetic field used for the ADR cycle, enabling synchronized, high-frequency operation without moving parts, gases, or complex valves, and supporting scalable multi-stage sub-Kelvin cooling.

Commercial Applications

• Cryogenic cooling for superconducting and spin-based quantum computers
• Low-temperature platforms for quantum sensing, metrology, and fundamental physics
• Space and defense cryogenic instrumentation requiring vibration-free cooling
• Compact, closed-cycle sub-Kelvin refrigerators for research and industrial cryogenics

Benefits/Advantages

• All-solid-state design: Eliminates mechanical wear, gas handling, and reliability issues of conventional thermal switches
• Helium-3 free: Reduces cost, supply-chain risk, and environmental constraints
• High-speed operation: Switch frequency limited primarily by magnetic field cycling, enabling higher cooling power
• Bipolar switching with one field: Simplifies system architecture and enables efficient multi-stage ADR integration