Controlling dipole transparency with magnetic fields

We describe how magnetic fields can be exploited to control dipole-induced transparency in quantum dot cavity systems. Coupling a linearly-polarized microcavity mode to two spin charged exciton states of a single quantum dot, we demonstrate how cavity-mediated interference and magnetic-field resonance shifts can be utilized to control the transmission of light and on-chip photons, in both magnitude and phase. In particular, we show a triple resonance feature, which also survives with weakly coupled cavities, as long as one operates in the good cooperativity regime. The central peak, which is mediated by the applied magnetic field, is shown to exhibit spectral squeezing. We also demonstrate how the magnetic field allows five regions in which the phase changes by 2π over a small frequency window, where a possible phase gate could be implemented.