Photonic circuits for single rare-earth emitters

• Applicant: Dr. Roman Kolesov
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 262528081

The goal of the project is to incorporate single rare-earth (RE) emitters doped into crystalline solids into photonic networks for quantum information processing. The project is based on recent achievements in detecting RE dopants in crystals at a single ion level [1,2,3], on rigorous studies of their spin properties [4], and on demonstrated waveguiding properties of the host crystalline materials prepared in a form of thin film on a low refractive index substrate [5,6]. The proposed approach allows for technologically simple implementation of a variety of photonic elements such as waveguides, cavities, beamsplitters, on-chip laser sources, etc. with the desired RE species incorporated in these elements. The main advantage of RE-based systems, if compared to other approaches to quantum network architectures based on quantum dots (QDs) and nitrogen-vacancy (NV) centers in diamond is their potential integrability. The problems of QDs and NV centers, such as deterministic positioning inside photonic structures, spectral diffusion, and blinking, are significantly relaxed, if present at all, in RE-based systems. Additional advantage of these systems comes from highly developed thin film technology allowing for almost arbitrary shaping of the host crystalline material without affecting the coherence properties of RE centers. Once accomplished, the present project will allow for technologically advantageous way of establishing on-chip light-matter interfaces. In particular, it will allow for realization of on-chip narrow-band single photon emitters, two-photon interference, and spin-photon entanglement crucial for quantum error correction in scalable quantum networks. Apart from technological advantages, the proposed approach might have significant impact in basic research since it allows for studying cavity quantum electrodynamics (Cavity QED) effects in solid state systems involving a few or even one emitter and controllable number of photons in the cavity. These effects include optical bistability, conditional phase shifts, etc. Furthermore, it opens a possibility of studying physical phenomena related to photon hopping in arrays of cavities. The most intriguing would be Majorana-like light modes in cavity chains and quantum phase transitions in cavity lattices.

• DFG Programme: Research Grants