Researchers from the University of Paris-Saclay, the University of Regensburg and the University of Jyvaskyla have delivered a combined experimental and theoretical work revealing the profound nature of quantum transport in strongly driven diffusive Josephson junctions.
They have studied the out-of-equilibrium dynamical state induced by the absorption of high frequency microwave photons in diffusive superconductor-normal metal-superconductor (SNS) junction. To characterize this state, the researchers pioneered a harmonic-resolved ac-Josephson spectroscopy technique to access the harmonic content of the current-phase relation under microwave radiation.
The team discovered that a strong anharmonicity of the current-phase relation arises under illumination, especially at high frequency when inelastic transitions across the induced mini-gap are favored. This novel regime goes well beyond the standard Eliashberg theory and is understood because of the modifications of the supercurrent-carrying Andreev spectrum induced by non-adiabatic transitions.
These findings have important implications in Andreev-based quantum computing prospects. (Phys.org)
