Extremely weak electron-phonon coupling in Josephson junctions built on InAs on Insulator

InAs-on-Insulator (InAsOI) enables an effective superconducting proximity effect and extremely weak electron-phonon (e-ph) coupling, allowing precise electronic-temperature control with minimal power. Using Josephson junction thermometry, we extract sub-Kelvin e-ph coupling parameters, confirming strong thermal decoupling and robust superconducting performance. The combination of weak e-ph interaction and full electrostatic tunability makes InAsOI a powerful platform for coherent caloritronics, ultrasensitive bolometry, single-photon detection, and gate-controlled superconducting thermal circuits.