Recently, there has been intense activity in developing diamond as a quantum platform, driven by the discovery of defects that can be addressed optically and have long spin coherence times, enabling quantum control using optical microscopy. I will describe materials engineering efforts to control and explore these systems.
This talk will focus on the development of material platforms and physical mechanisms for high-fidelity control, storage, and transmission of quantum information. In particular, emerging quantum materials - novel diamond impurities - featuring long-lived, optically addressable quantum states are promising candidates fulfilling most of these requirements. We will discuss possible mechanisms for efficient interfacing of these novel solid-state qubits, in particular allowing for high-fidelity quantum-state transduction to superconducting qubits or to the long-lived nuclear spins. Finally, the physical phenomena enabling local quantum control in these materials, including strain-mediated or optically mediated state-transfer and two-qubit gates, will be discussed.
As the field of solid-state quantum engineering matures, it is increasingly necessary to produce quantum emitters with narrow optical transitions and long spin coherence times aligned to nanophotonic structures [1]. The nitrogen-vacancy (NV) defect center in diamond is a well-suited candidate owing to a spin ground state with a long coherence time [2], nearby nuclear spins for quantum memories [3], and spin-selective optical transitions allowing for efficient optical spin initialization and readout [4].
Coherent control and readout of single spins in solids is attracting considerable attention, owing to potential application of atomic- scale technologies in novel information processing protocols and sensing at the nanoscale [38]. Spins are particularly interesting candidates for achieving such control, owing to the long coherence time. This isolation from the environment makes the readout of individual spins quite challenging. It was shown that the magnetic moment associated with single quantum systems can be detected in transport measurements with single quantum dots [25] and defects in silicon [81]. Magnetic resonance force microscopy was also able to reach the ultimate sensitivity regime [65]. Recently developed optical readout techniques explore new avenue in single-spin de- tection by combining high-sensitivity optical microscopy techniques and conventional magnetic resonance control methods. Following detection of single molecular spin [80], quantum states associated with single defects in diamond were explored [29]. Experiments with single defects in diamond are particularly interesting owing to the long coherence time associated with spins of color centers. This chapter shows the basics of single-spin detection and highlights the importance of coherent control of spins in solids for novel quantum technologies.
Solid-state color-center spin defects provide a versatile platform for quantum sensing with applications ranging from nanoscale magnetometry to thermometry and electrometry. This review surveys recent progress in nitrogen-vacancy centers in diamond and defect spins in silicon carbide (SiC), with emphasis on their material properties, fabrication strategies, and coherence engineering. Key defect creation and optimization techniques, including ion implantation, femtosecond laser writing, focused ion beam nanofabrication, isotopic engineering, and surface passivation, are discussed in the context of improving spin coherence and optical performance. Fundamental quantum measurement protocols, optically detected magnetic resonance, Rabi oscillations, Ramsey interferometry, and spin echo, are reviewed as a hierarchical framework for characterizing spin control, dephasing, and intrinsic coherence. The review further highlights microscale sensing architectures and examines the growing role of machine learning in pulse optimization, adaptive estimation, and data-driven imaging. Finally, current challenges and future directions are outlined, focusing on scalability, environmental robustness, and autonomous operation. Together, these developments position diamond and SiC color centers as leading platforms for next-generation solid-state quantum sensors.