- The paper introduces a robust technique for deterministic coupling of a single NV center to a photonic crystal cavity using scanning microscopy.
- The method achieves precise nanoscale alignment (~80 nm resolution) with ~80% membrane transfer success and cavity Q factors around 6000.
- Photoluminescence results reveal NV lifetimes reduced from 16.4 ns to 12.7 ns, demonstrating a spectral enhancement factor of approximately 7.
Deterministic Coupling of a Single Nitrogen Vacancy Center to a Photonic Crystal Cavity
The paper presents a robust technique for deterministic coupling between a photonic crystal (PC) nanocavity and single nitrogen vacancy (NV) centers in diamond. By employing a scanning cavity microscope (SCM), the authors achieve nanoscale positioning of the PC cavity over desired emitters, an advancement that holds significant implications for quantum networking applications. The method demonstrated here utilizes a scanning approach to enable efficient interfacing of optical emitters with PC nanocavities, presenting a step forward in cavity quantum electrodynamics (QED) applications.
The approach is centered on the effective manipulation of a micron-scale PC slab, supported by a gallium phosphide (GaP) membrane, over diamond nanocrystals containing NV centers. The scanning method ensures careful alignment between the cavity and the emitter, verified through photoluminescence imaging. The results show enhanced coupling of NV center emissions due to their interaction with the PC nanocavity. This deterministic interaction is proven by illustrating large quality factors and high spontaneity emission modification, a key aspect of the proposed method.
After the PC slabs are fabricated using electron beam lithography, they are coupled with NV centers through a series of precise transfers and positioning techniques. The integration process attains ~80% success for each slab membrane, maintaining clear optical pathway integrity. The cavity itself is characterized by a quality factor (Q) of around 6000 post-transfer, though systematic investigations were conducted on cavities with Q values below 1000 to ensure reproducibility.
Significant numerical results are evidenced through variations in the emission lifetimes. For instance, the lifetime of uncoupled NV centers was measured at 16.4 ns, while NV centers coupled to the cavity experienced a reduced lifetime of 12.7 ns. These observations indicate a spectral enhancement factor of around 7.0, pointing to the strong effect of the cavity field on the emitter.
In a detailed experimental arrangement, the coupling is further quantified by changes in intensity correlated with PC positioning, highlighting precision alignments at a resolution of approximately 80 nm. The authors employ a multi-faceted spectroscopy approach to delineate the contributions from NV and cavity emissions and leverage spontaneous emission rate enhancement to better characterize the cavity-emitter interaction. The work elucidates the distinction between zero phonon line emissions and broader phonon sidebands, pushing forward the ability to direct emissions into channels suitable for coherent optical manipulation.
Theoretically, deterministic NV-cavity coupling promises improved outcomes in quantum information processing, notably in memory node operations within quantum networks and repeaters. The paper outlines the scanning cavity technique's potential to serve as a novel approach to sub-wavelength imaging, offering advantages in both resolution and emission rate control. The initial demonstration of SCM, recording high photon collection rates exceeding 10 photons/s from a single NV, showcases the tool's efficiency. This represents advancements in the facilitation of label-free studies and high-resolution analysis of optical emitters near decay channels.
Overall, the deterministic coupling of NV centers to photonic crystal nanocavities as described in this paper advances both theoretical foundations and practical applications within the field of quantum photonics and information systems. Future research can explore the extended use of this coupling method for various solid-state qubits, broadening the applicability of SCM in cutting-edge quantum technology domains.