0-π phase-controllable thermal Josephson junction.

Area of Science:

• Condensed Matter Physics
• Quantum Technologies
• Nanoscale Heat Transfer

Background:

• Josephson junctions exhibit unique quantum phenomena in electrical currents.
• Thermal analogues of the Josephson effect involve coherent heat transfer.
• Controlling the phase bias in thermal Josephson junctions is challenging.

Purpose of the Study:

• To experimentally realize a thermal Josephson junction with controllable phase bias.
• To demonstrate precise control over coherent energy transfer direction.
• To explore applications in caloritronic logic devices.

Main Methods:

• Utilized a superconducting quantum interferometer to control the phase bias (ϕ) from 0 to π.
• Fabricated a completely superconducting system for thermal transport measurements.
• Measured temperature modulations and transfer coefficients at cryogenic temperatures (25 mK).

Main Results:

• Achieved the first experimental realization of a phase-bias-controllable thermal Josephson junction.
• Demonstrated unprecedented temperature modulations of ~100 mK.
• Observed high transfer coefficients exceeding 1 K per flux quantum.

Conclusions:

• The developed quantum structure is a fundamental step towards caloritronic logic components.
• Enables realization of thermal transistors, switches, and memory devices.
• Offers potential benefits for cryogenic microcircuits, quantum computing, and radiation sensors.