We investigate spontaneous emission properties and control of the zero phonon line （ZPL） from a diamond nitrogen- vacancy （NV） center coherently driven by a single ellipfically polarized control field. We use the Schrrdinger equation to calculate the probability amplitudes of the wave function of the coupled system and derive analytical expressions of the spontaneous emission spectra. The numerical results show that a few interesting phenomena such as enhancement, narrowing, suppression, and quenching of the ZPL spontaneous emission can be realized by modulating the polarization- dependent phase, the Zeeman shift, and the intensity of the control field in our system. In the dressed-state picture of the control field, we find that multiple spontaneously generated coherence arises due to three close-lying states decaying to the same state. These results are useful in real experiments.
This paper gives a brief introduction to our recent works on photonic crystal(Ph C) cavities and related integrated optical structures and devices. Theoretical background and numerical methods for simulation of Ph C cavities are first presented. Based on the theoretical basis, two relevant quantities, the cavity mode volume and the quality factor are discussed. Then the methods of fabrication and characterization of silicon Ph C slab cavities are introduced. Several types of Ph C cavities are presented, such as the usual L3 missing-hole cavity, the new concept waveguide-like parallel-hetero cavity, and the low-index nanobeam cavity. The advantages and disadvantages of each type of cavity are discussed. This will help the readers to decide which type of Ph C cavities to use in particular applications. Furthermore, several integrated optical devices based on Ph C cavities, such as optical filters, channel-drop filters, optical switches, and optical logic gates are described in both the working principle and operation characteristics. These devices designed and realized in our group demonstrate the wide range of applications of Ph C cavities and offer possible solutions to some integrated optical problems.
We investigate the properties of entanglement and cxcited-state quantum phase transition (ESQPT) in a hybrid atoin-optoinochaiiical system in which ail optomechanical quadratic interaction is introduced into a normal Dickc model.Interestingly,by preparing the ancillary mode in a coherent state,both the quantum entanglement and ESQPT can be realized in a relative wcak-coupling condition.Moreover,the entanglement is immune to the A^2 term,and a reversed trend of the entropy is obtained when the A^2 term is included.Density of states (DoS) and Peres lattice are used to investigate ESQPTs.Compared to a normal Dicko model,the DoS enlarges exp(2rα) times if the ancillary mode is prepared in a coherent state.This work is an extension of the ground-state quantum phase transition,which may inspire further exploration of the quantum criticality in many-body systems.
