Universal dielectric loss in amorphous solids in Josephson qubits from simultaneous bias and microwave fields

We calculate the microwave dielectric loss of an ensemble of two-level systems in amorphous solids within superconducting qubits during the application of a time-varying electric bias field. We find that this loss becomes universal in a wide range of temperatures and frequencies of the AC drive field, corresponding to the bare linear dielectric permittivity in the low-temperature limit. This non-equilibrium theory allows the separate extraction of the TLS density and their dipole size in experiments and can be used to reduce the destructive effect of decoherence.