Giant quantum electrodynamic effects on single SiV color centers in nanosized diamonds

Understanding and mastering quantum electrodynamics phenomena is essential to the development of quantum nanophotonics applications. While tailoring of the local vacuum field has been widely used to tune the luminescence rate and directionality of a quantum emitter, its impact on their transition energies is barely investigated and exploited. Fluorescent defects in nanosized diamonds constitute an attractive nanophotonic platform to investigate the Lamb shift of an emitter embedded in a dielectric nanostructure with high refractive index. Using spectral and time-resolved optical spectroscopy of single SiV defects, we unveil blue shifts (up to 80 meV) of their emission lines, which are interpreted from model calculations as giant Lamb shifts. Moreover, evidence for a positive correlation between their fluorescence decay rates and emission line widths is observed, as a signature of modifications not only of the photonic local density of states but also of the phononic one, as the nanodiamond size is decreased. Correlative light–electron microscopy of single SiVs and their host nanodiamonds further supports these findings. These results make nanodiamond-SiVs promising as optically driven spin qubits and quantum light sources tunable through nanoscale tailoring of vacuum-field fluctuations.We acknowledge the financial support from the French National Agency for Research, Région Nouvelle-Aquitaine, Idex Bordeaux (Research Program GPR Light), the EUR Light S&T (PIA3 Program, ANR-17-EURE0027), and the Laboratory for Transborder Cooperation LTC TRANS-LIGHT from University of Bordeaux and University of the Basque Country. B.L. acknowledges the Institut Universitaire de France. R.E. and J.A. acknowledge financial support from the Basque Government for consolidated groups of the Basque University (Grant IT 1526-22) and MCIN/AEI/10.13039/501100011033/(Grant PID2019-107432GB-I00).Peer reviewe

Micro- and nanodiamonds doped with nitrogen-vacancy centers for nuclear spin hyperpolarization

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are important noninvasive analytical tools for material characterization. However, the low thermal polarization of nuclear spins imposes a limitation on the sensitivity of conventional nuclear magnetic resonance and imaging techniques. Dynamic nuclear polarization (DNP) provides significant gains in magnetic resonance signals and can drastically increase the sensitivity of NMR and MRI techniques. This work explores nuclear hyperpolarization using paramagnetic defects in nanodiamonds. The negatively charged Nitrogen-Vacancy (NV) center in diamond can be optically polarized at room temperature to a high degree (>90 %) under green light illumination. Transferring high NV polarization to nuclear spins can increase nuclear polarization up to a million times higher than thermal equilibrium. Unlike conventional DNP, hyperpolarization with NV centers does not require cryogenic temperatures or high magnetic fields, making NV centers an attractive platform for nuclear polarization. Functionalized diamond nanoparticles are biocompatible and have low toxicity compared to other nanomaterials. Nanodiamonds (NDs) are proven useful for therapeutic drug delivery and can be potentially used as bioprobes. Hyperpolarization of 13C nuclear spins in NDs can also enable new modalities for highly sensitive MRI tracking. One of the most important factors for the success of NDs in these applications is the requirement for suitable diamond material properties. Firstly, certain ND synthesis and treatment techniques are used to improve the material properties of diamond powders to allow efficient polarization transfer from NV centers to nuclear spins. The obtained diamond powders are analyzed with the following spectroscopic techniques: Electronic Paramagnetic Resonance (EPR), NMR, and Optically Detected Magnetic Resonance (ODMR). Next, we adapted the hyperpolarization technique for experimental use with diamond powders. Finally, using the material with improved properties, we implement hyperpolarization of 13C nuclear spins via NV centers in nano- and microdiamond particles, using a combined EPR-NMR system. The results obtained in this work can motivate further research towards implementation of NDs for MRI application

“Core–Shell” Diamond Nanoparticles with NV – Centers and a Highly Isotopically Enriched 13 C Shell as a Promising Hyperpolarization Agent

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Synthesis and coherent properties of 13C enriched sub-micron diamond particles with nitrogen vacancy color centers

International audienceHere we report the synthesis of 13C enriched diamond powder with sub-micron particle sizes via High Pressure High Temperature (HPHT) growth. Diamond powder with a tailored isotopic enrichment is particularly interesting for implementation of Dynamic Nuclear spin Polarization (DNP) and 13C enrichment plays an important role for increasing the signal to noise ratio in Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging. We applied Electron Paramagnetic Resonance (EPR) and NMR spectroscopy to the sub-micron diamond material as well as Optically Detected Magnetic Resonance (ODMR) and atomic force microscopy to investigate preselected nano-sized particles. The 13C spin concentrations were evaluated with NMR for the initial particle ensemble and with ODMR for the nanodiamond fraction, showing the homogeneous distribution of 13C density in particles with different sizes. The 13C nuclear spin-lattice relaxation decay () shows a multiexponential behavior, where the fast relaxing component is attributed to relaxation from surface defects. Additionally, an optical method for estimating the NV− concentration in nanodiamonds is presented. The obtained powder is promising as a base material for the production of 13C-enriched nanodiamonds for DNP applications

Synthesis and coherent properties of C-13-enriched sub-micron diamond particles with nitrogen vacancy color centers

Here we report the synthesis of 13C-enriched diamond powder with sub-micron particle sizes via High Pressure High Temperature (HPHT) growth. Diamond powder with a tailored isotopic enrichment is particularly interesting for implementation of Dynamic Nuclear spin Polarization (DNP) and 13C enrichment plays an important role for increasing the signal to noise ratio in Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging. We applied Electron Paramagnetic Resonance (EPR) and NMR spectroscopy to the sub-micron diamond material as well as Optically Detected Magnetic Resonance (ODMR) and atomic force microscopy to investigate preselected nano-sized particles. The 13C spin concentrations were evaluated with NMR for the initial particle ensemble and with ODMR for the nanodiamond fraction, showing the homogeneous distribution of 13C density in particles with different sizes. The 13C nuclear spin-lattice relaxation decay () shows a multiexponential behavior, where the fast relaxing component is attributed to relaxation from surface defects. Additionally, an optical method for estimating the NV− concentration in nanodiamonds is presented. The obtained powder is promising as a base material for the production of 13C-enriched nanodiamonds for DNP applications

Nanoscale Dynamic Readout of a Chemical Redox Process Using Radicals Coupled with Nitrogen-Vacancy Centers in Nanodiamonds

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Nanoscale Dynamic Readout of a Chemical Redox Process Using Radicals Coupled with Nitrogen-Vacancy Centers in Nanodiamonds

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