Time-dependent electron transport through an Aharonov-Bohm ring embedded with two quantum dots

The time-dependent electron transport through an Aharonov-Bohm ring embedded with two quantum dots in the presence of external microwave (MW) fields are investigated theoretically by using the nonequilibrium Green's function method. Whether the MW field can induce or suppress the Fano resonance depends on the part to which the field is applied. When the MW field is applied only to the two quantum dots, the photon-assisted Fano peaks appear at the sidebands of the original Fano peak. The existence of the original Fano peak or the photon-assisted ones can be controlled by the field strength. When the MW field is applied only to one lead, the original Fano peak is suppressed by the MW field, and the negative current caused by the electron-photon pump effects is found.