This chapter is organized as follows: The first half of the chapter is about quantum light sources based on diamond color centers. After the introduction in Section 7.1, we discuss the optical properties of the NV center and other color centers in diamond, indistinguishable photon sources in diamond, entanglement between photon and spin in diamond, electroluminescence (EL) of color centers in diamond, and diamond nanophotonic devices. The second half of the chapter is about quantum light sources based on color centers in SiC. Mainly, fundamental characteristics of silicon vacancies and divacancies are presented in each section.
This chapter is organized as follows: The first half of the chapter is about quantum light sources based on diamond color centers. After the introduction in Section 7.1, we discuss the optical properties of the NV center and other color centers in diamond, indistinguishable photon sources in diamond, entanglement between photon and spin in diamond, electroluminescence (EL) of color centers in diamond, and diamond nanophotonic devices. The second half of the chapter is about quantum light sources based on color centers in SiC. Mainly, fundamental characteristics of silicon vacancies and divacancies are presented in each section.
Light emission from color centers in diamond is being extensively investigated for developing, among other quantum devices, single-photon sources operating at room temperature. By doping diamond with phosphorus, one obtains an n-type semiconductor, which can be exploited for the electrical excitation of color centers. Here, we discuss the optical properties of color centers in phosphorus-doped diamond, especially the silicon-vacancy center, presenting the single-photon emission characteristics and the temperature dependence aiming for electroluminescent single-photon emitting devices.
Chapter 1 reviews recent advances towards the realization of quantum networks based on atom-like solid-state quantum emitters coupled to nanophotonic devices. Specifically, focus is on experiments involving the negatively charged silicon-vacancy color center in diamond. These emitters combine homogeneous, coherent optical transitions and a long-lived electronic spin quantum memory. Optical and spin properties of this system at cryogenic temperatures and experiments where silicon-vacancy centers are coupled to nanophotonic cavities are discussed. Finally, the chapter discusses experiments demonstrating quantum nonlinearities at the single-photon level and two-emitter entanglement in a single nanophotonic device.
Optical sources that deliver single photons on demand play a key role in quantum cryptography and optical quantum computations. At present, color centers in wide-bandgap semiconductors, such as the nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers in diamond, are considered to be the most promising candidates for practical quantum information applications owing to their unique emission properties at room temperature. However, for practical reasons, single-photon sources should be pumped electrically, which is required for integrability, scalability, and energy efficiency. However, diamond and related wide-bandgap semiconductor materials are at the interface between insulators and semiconductors, which makes electrical excitation of color centers very challenging. Here, we report on our progress in the understanding of single-photon electroluminescence of color centers in diamond, discuss different factors affecting the brightness of these emitter under electrical excitation, and study how to improve the performance of electrically- pumped single-photon sources based on color centers in diamond.
Solid-state single-photon sources are the central blocks for many scalable quantum applications including quantum computing, quantum key distributions, and quantum simulations. Over the years, diverse quantum emitters have been studied. This thesis endeavored investigations into single-photon sources in diamond, silicon carbide and gallium nitride in three directions: Firstly, identification of the single-photon sources that have never been reported before and fabrication technique for scalable single germanium vacancy centers in diamond. Telecom wavelength single photon sources have been found in both gallium nitride and silicon carbide. More importantly, those emitters work even at room temperature and are promising for quantum key distribution applications in the future. Secondly, the spin properties study of the single silicon vacancy in diamond: the silicon vacancy optical transition has been coherently controlled in the work. The optical Rabi oscillations in the time domain have been observed. The ultrafast spin control of the silicon vacancy has been also achieved. Thirdly, quantum applications of the divacancy spins in silicon carbide: nano-scale thermometry based on the quantum control of the divacancy spin in silicon carbide has been introduced. Especially, we found a self-protected effect that the transverse strain can protect the spin from the local magnetic field and enables longer coherence time. Finally, some possible directions have been discussed.
ABSTRACT Quantum computing leverages the principles of quantum mechanics to perform computations that are infeasible for classical computers. Color centers, which are point defects in a crystal lattice where vacancies in the lattice and/or an impurity atom replace a host atom, exhibit unique optical, electronic, and nuclear spin properties that make them suitable for quantum information and communication processing as well as for quantum computations with quantum memory. Among the color centers, nitrogen‐vacancy centers in diamond, the most developed, silicon vacancy (V Si ) centers in silicon carbide (SiC), and boron vacancy (V B ) centers in hexagonal boron nitride (hBN) have emerged as leading candidates. Diamond and SiC material hosts are particularly promising due to the long spin and photon coherence times, optical addressability, compatibility with various quantum operations, while SiC promises higher compatibility with scalable industrial fabrication processing, and 2D materials are better suited for hybrid photonics and electronics integration. This paper provides a detailed overview of the advantages, challenges, and recent advancements in using these color centers for quantum computing. In addition, it discusses other potential color centers of interest, such as silicon (SiV) and germanium (GeV) vacancies in diamond, tin vacancies (SnV) in diamond, chromium and nickel centers in diamond, and rare‐earth ions in host materials like yttrium orthosilicate and calcium fluoride. By understanding and utilizing the properties of these diverse color centers, researchers aim to develop more efficient, scalable, and versatile quantum computers, which could lead to hybrid quantum‐classical systems that combine the strengths of different platforms and potentially transform fields like cryptography, material science, drug discovery, and complex system simulations (climate modeling, fusion energy).