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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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Acoustic wave transparency in nitrogen-vacancy centers in a photonic crystal
摘要： We show that the interaction of nitrogen-vacancy centers in diamond with a strain field in a photonic crystal can lead to acoustic wave transparency. This occurs due to the strong interaction of photons with the modified photonic reservoir near the photonic band edge created by the photonic crystal. For achieving this, we explore the properties of the spin states of the ground state of the nitrogen-vacancy centers, where one transition interacts with a strain field while the other transition has spontaneous emission that occurs near the edge of the photonic band gap, which should be in the microwave regime. We show that depending on the form of the photonic density of states acoustic wave transparency is obtained at one or two frequencies.
关键词： Induced transparency,Photonic crystal,Non-Markovian dynamics,Acoustic field,Nitrogen-vacancy center in diamond
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Fabrication of High Quality Quantum Emitters in Diamond Nanostructures
摘要： 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. The nitrogen-vacancy (NV) defect center in diamond is a well-suited candidate owing to a spin ground state with a long coherence time, nearby nuclear spins for quantum memories, and spin-selective optical transitions allowing for efficient optical spin initialization and readout. We demonstrate an emitter-device alignment technique enabling fabrication of photonic devices registered to NVs. The alignment method relies on autonomously imaging emitters and registering them relative to an on-chip coordinate system. This technique can be performed on a large variety of emitters. The repeatability of this method suggests a spatial accuracy of 50 nm. The ability to navigate a sample autonomously facilitates data collection on a large number of NVs, thus permitting statistical analyses. We utilized this approach to correlate the NV’s host nitrogen isotope with the optical linewidth of the emitter to understand the effects of implantation. As shown in Fig. 1a, the data indicate that the coherent, narrow-linewidth NVs are formed from naturally abundant nitrogen (14N), whereas the implanted nitrogens (15N), on average, yield broader linewidth NVs. The implanted 15NVs also exhibit larger axial and transverse strains suggesting that damage was produced near the emitter. We attribute the broad linewidths of implanted 15NVs to a more volatile local environment generated by local damage resulting from the ion implantation process.
关键词： diamond nanostructures,nanophotonic structures,nitrogen-vacancy center,spin coherence,quantum emitters
更新于2025-09-16 10:30:52
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Hybrid spin-superconducting quantum circuit mediated by deterministically prepared entangled photonic states
摘要： In hybrid quantum systems, a controllable coupling can be obtained by mediating the interactions with dynamically introduced photons. We propose a hybrid quantum architecture consisting of two nitrogen vacancy center ensembles coupled to a tunable flux qubit, which is contained on the transmission line of a multimode nonlinear superconducting coplanar waveguide resonator with an appended Josephson mixing device. We discuss the use of entangled propagating microwaves photons, which through our nonlinear wave-mixing procedure are made into macroscopically distinct quantum states. We use these states to steer the system and show that, with further amplification, we can create a similar photonic state, which has a more distinct reduction of its uncertainty. Furthermore, we show that all of this leads to a lengthened coherence time, a reasonable fidelity that decays to 0.94 and then later increases upward to stabilize at 0.6, as well as a strengthened entanglement.
关键词： squeezed Schr?dinger cat state,entangled microwaves photons,Schr?dinger cat state,flux qubit,nitrogen vacancy center ensembles,superconducting coplanar waveguide resonator,hybrid quantum systems
更新于2025-09-12 10:27:22
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Noise spectroscopy of a quantum-classical environment with a diamond qubit
摘要： Knowing a quantum system’s environment is critical for its practical use as a quantum device. Qubit sensors can reconstruct the noise spectral density of a classical bath, provided long enough coherence time. Here, we present a protocol that can unravel the characteristics of a more complex environment, comprising both unknown coherently coupled quantum systems, and a larger quantum bath that can be modeled as a classical stochastic field. We exploit the rich environment of a nitrogen-vacancy center in diamond, tuning the environment behavior with a bias magnetic field, to experimentally demonstrate our method. We show how to reconstruct the noise spectral density even when limited by relatively short coherence times, and identify the local spin environment. Importantly, we demonstrate that the reconstructed model can have predictive power, describing the spin qubit dynamics under control sequences not used for noise spectroscopy, a feature critical for building robust quantum devices. At lower bias fields, where the effects of the quantum nature of the bath are more pronounced, we find that more than a single classical noise model are needed to properly describe the spin coherence under different controls, due to the back action of the qubit onto the bath.
关键词： nitrogen-vacancy center,diamond qubit,noise spectroscopy,dynamical decoupling,quantum-classical environment
更新于2025-09-09 09:28:46
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Imaging the Local Charge Environment of Nitrogen-Vacancy Centers in Diamond
摘要： Characterizing the local internal environment surrounding solid-state spin defects is crucial to harnessing them as nanoscale sensors of external fields. This is especially germane to the case of defect ensembles which can exhibit a complex interplay between interactions, internal fields, and lattice strain. Working with the nitrogen-vacancy (NV) center in diamond, we demonstrate that local electric fields dominate the magnetic resonance behavior of NV ensembles at a low magnetic field. We introduce a simple microscopic model that quantitatively captures the observed spectra for samples with NV concentrations spanning more than two orders of magnitude. Motivated by this understanding, we propose and implement a novel method for the nanoscale localization of individual charges within the diamond lattice; our approach relies upon the fact that the charge induces a NV dark state which depends on the electric field orientation.
关键词： diamond,local electric fields,nanoscale localization,nitrogen-vacancy center,magnetic resonance
更新于2025-09-04 15:30:14