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Strong polarization of individual nuclear spins weakly coupled to nitrogen-vacancy color centers in diamond
摘要： We experimentally demonstrate high degree of polarization of 13C nuclear spins weakly interacting with nitrogen-vacancy (NV) centers in diamond. We combine coherent microwave excitation pulses with optical illumination to provide controlled relaxation and achieve a polarity-tunable, fast nuclear polarization of degree higher than 85% at room temperature for remote 13C nuclear spins exhibiting hyperfine interaction strength with NV centers of the order of 600 kHz. We show with the aid of numerical simulation that the anisotropic hyperfine tensor components naturally provide a route to control spin mixing parameter so that highly efficient nuclear polarization is enabled through careful tuning of nuclear quantization axis by external magnetic field. We further discuss spin dynamics and wide applicability of this method to various target 13C nuclear spins around the NV center electron spin. The proposed control method demonstrates an efficient and versatile route to realize, for example, high-fidelity spin register initialization and quantum metrology using nuclear spin resources in solids.
关键词： nitrogen-vacancy (NV),nitrogen-vacancy center,spin initialization,hyperfine interaction,spin polarization
更新于2025-09-23 15:19:57
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Rapid Optical Spin Initialization of a Quantum Dot in the Voigt Geometry Coupled to a Two-Dimensional Semiconductor
摘要： We study the interaction of a quantum dot in the Voigt con?guration with a laser pulse and particularly analyze the potential for rapid spin initialization by putting the quantum dot near a molybdenum disul?de (MoS2) monolayer. The MoS2 monolayer in?uences the spontaneous decay rates of the quantum dot, leading to anisotropically enhanced decay rates, for the quantum dot’s electric dipole moments parallel and perpendicular to the layer. By solving the relevant density matrix equations, we ?nd that high spin initialization ?delity is obtained at short times. The ?delity is signi?cantly higher than when the quantum dot is in free-space vacuum. We examine two different cases of the interaction of the quantum dot with the applied optical ?eld. First, we use a continuous wave laser ?eld and determine for various quantum dot—MoS2 layer distances the ?eld strength that leads to acceptable ?delity levels. The effect of the quality of the MoS2 material on the ?delity of spin initialization is also examined. We also study the interaction of the quantum dot with a laser pulse and apply numerical optimal control to obtain the time-dependent ?eld strength, which leads to maximum ?nal ?delity for short time intervals. The latter approach gives bene?cial results in comparison to the continuous wave ?eld excitation.
关键词： spin initialization,quantum dot,Voigt geometry,optical pumping,Purcell effect,optimal control,spin dynamics
更新于2025-09-23 15:19:57