Ph.D Thesis

Ph.D StudentJaffe Tzach
SubjectQuantum-Photonic Systems based on Color Centers in
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Meir Orenstein
Full Thesis textFull thesis text - English Version


For many years, single atoms and atom-like systems have drawn the attention of researchers due to the great controllability they exhibit over both internal and external degrees of freedom. Solid state quantum systems, where individual atoms are fixed relative to each other, possess a wide span of different degrees of freedom including super conducting flux qubits, spin degree of freedom in Quantum dots and mechanical resonances.  Most of these systems, adversely, require a very low operation temperature since they are strongly coupled to external perturbations such as vibrations, excitations and electron spin baths.  One superb candidate for hosting a solid state quantum system is the diamond, a large bandgap material that can be grown with controlled sub-ppb impurity concentration and also in an isotopically purified form to rule out magnetic noise from nuclear spins in the quantum system surrounding. Furthermore, due to diamond large band gap a variety of deep color defects with optical accessibility can be created. 

In this work we explore color centers in diamond while controlling the quality of the diamond host on one hand and governing the photonic out-coupling and interaction through coupling to nanophotonic systems on the other. This degree of control is essential for realizing enhanced nanoscale magnetic sensors and single-photon sources. First, we demonstrate, theoretically and experimentally, the potential of using plasmonic nano-antennas on top of diamond bulk substrate for spatial control over initialization and readout of shallow ensembles of Nitrogen-Vacancy (NV) center spin states with polarization and wavelength selectivity at a highly localized spot (30nm)1. We point out a clear signature of enhanced light-matter interaction by obtaining an intrinsic photoluminescence enhancement of order of magnitude from NV centers within the hot spot of the antenna area as well as similar emission lifetime reduction. The higher emission rate and collection efficiency are key issues towards realizing NV-based ODMR magnetometers.  Next, we present a template-assisted bottom-up method for creating robust, deterministic and high-quality diamond nano-pyramid arrays incorporating Silicon-Vacancy (SiV) centers for single-photon source applications2. In this work we incorporate the benefits of both, diamond nanostructuring and of high-quality diamond crystal hosting the quantum sources. We present a comprehensive characterization of the nano-pyramid structure revealing it is homoepitaxial providing a good ambient for optical performance of the SiVs3. These promising color centers in diamond are potential high-quality single photon sources with a bright narrow-band and spectrally stable optical transition operating at room temperature. Finally, we develop and demonstrate the realization of a dense delta-doped layer of NV centers created by plasma nitridation process with nanometric thickness showing competitive ODMR characteristics. This method preserve the diamond host quality as confirmed by HREELS analysis and offers a finer control over the concentration (1e20 cm-3 nitrogen concentration) and thickness of the delta-doped layer than the currently used techniques. The ability to fabricate delta-doped layers with a high concentration of NV ensembles confined within an atomic layer paves the way towards highly sensitive NV-based magnetometers.