Flux quantized energy oscillations upon microwave excitation of high temperature superconductors

We find that the imaginary part of the complex susceptibility as a function of magnetic field at a frequency of 9.2 GHz shows equally spaced lines indicating harmonic oscillator type of excitations. The maximum in d ξ″ d H is also found to be proportional to the life time of the electron in the normal state. The predictions are verified by using the microwave absorption in ErBa2Cu3O7−δ and YBa2Cu3O7−δ (δ ≃ 0.2).